- Manufacturer & Model
-
Matrix Audio mini-i Pro 4
Topping DX9
S.M.S.L. DO400
HIFIMAN Goldenwave Serenade
RME ADI-2 DAC FS
Aune S17 Pro Class A Amp
JDS Labs Atom Amp 2
iBasso DX180 DAP
- MSRP
- $272.99 to $1299
- Summary
-
Comparing headphone amps is a delicate and time-consuming process that may even test your integrity. However, it can also be a rewarding and fun experience that helps us decide which amp is right for our needs. In this event, I will compare eight headphone amps to determine which ones will settle permanently in our home.
Headphone Amp Comparison: Matrix Audio mini-i Pro 4 vs. Topping DX9 vs. S.M.S.L DO400 vs. HIFIMAN Goldenwave Serenade vs. RME ADI-2 DAC FS vs. Aune S17 Pro Class A Amp vs. JDS Labs Atom Amp 2 vs. iBasso DX180 DAP
Introduction
In my search for a couple of headphone DAC amps, I thought it would be an excellent opportunity to share my thoughts about the comparisons I made. This is not only a comparison of several headphone amps, but it will also compare the WiiM Ultra vs. the Matrix i-mini Pro 4 vs. the Eversolo DMP-A6 as preamp streamers. There will also be an iFi SilentPower LAN iPurifier Pro in the loop on some of the amps while being compared to others not looped through the iPurifier. There will be various cables, from generic to what we might consider mid-fi range… nothing abhorrently expensive. This is mainly to ensure we don’t have a bad cable in the chain. In other words, it will be a good mix of comparisons.
Note: You should be able to click on the graphs throughout the article to see a larger image. If you are using a phone, you may want to view the graphs in landscape mode and enlarge them.
The Never-ending Debate
It wouldn’t be appropriate to dive into an amp comparison without some history on the never-ending debate. Are there audible differences in amps? In this comparison, it will be specifically for headphone amps. Better worded for my benefit, are there enough audible differences between headphone amps to cause me to want to buy one over the other? This is really for my satisfaction because it’s fun and exciting for me. Let me somewhat ramble here about the hot debate. There is so much controversy about whether we can hear differences in amps that it’s enough to cause nausea for some folk. We can throw DACs in the pile with amps, especially when considering headphone amp comparisons, as many include DACs. I want to make it very clear that I’ve never said that no one can hear differences, but I have said that I can’t and that amps should be transparent... or neutral... not adding or taking away from the sound; therefore, we shouldn’t hear differences if they are doing their job of reproducing the music in an unaltered fashion. If there are differences, they are likely very subtle and not as drastic as some make them out to be. I hear some pretty remarkable comments about differences in amps that I suspect if the person making those comments were to be confronted with a controlled blind amp test, that person might be embarrassed… just a hunch. While one person is singing praises because an amp sounds great with a particular speaker or headphone, another says it sounds terrible or doesn’t work with that same speaker or headphones. A sounds better than B, B sounds better than C, and C sounds better than D. Just how much better is A than D? Maybe we need to discard D and fire the manufacturer if it’s that bad.
Consider the guy who claimed a startling improvement in sound, a wider soundstage, and better clarity when he changed out his headphone amp. He seemed to have justified spending the extra money on the amp and was tickled pink with his decision. He then changed the power supply on the amp and discovered an even broader soundstage and more air in the music. Then, he changed out his DAC/streamer to uncover an even better soundstage and other improvements. Later, he upgraded his USB cable from his DAC to his amp, and you guessed it, there were more improvements and a better soundstage. Keep in mind that he’s not expressing these as subtle improvements; instead, they are very noticeable improvements. Then, he decided to add an audiophile switch to his incoming fiber for another amazing improvement. That was so good he decided to get an Ethernet purifier to carry it one step further, which made yet another improvement. The upgraded power supply improved his DAC so much that he decided to upgrade the power supplies on the switch and the purifier to hear more improvements. Oh… he’s not done… he upgraded his headphone cables, and magic unfolded between his ears. But that’s not the end of it. He decided to try another more expensive headphone amp, and remarkedly, he sang hallelujah praises for the vast improvement it made. This guy went from tickled pink to tickled pinker than pink. Yes… I exaggerated a bit here in this fairytale, but look around; guys like this are all over the Internet claiming startling differences every time they change something in their system – mainly every time they buy something more expensive.
Most differences are likely from comparing with too much time between comparisons and failure to level match the volume. Other differences claimed are glorified in discussion forums because of hyped speculations, biased purchase justifications, and brainwashed or biased expectations without proof of any differences offered with controlled testing or objective measurements. There is not even an attempt at measuring anything. They expect you to take their word for it or go away because you're dumb if you disagree. Members seem to trust other members based on how many posts they have, the equipment they own or have owned, and how they write, even though most of them likely have no idea who they are trusting. Don’t get me wrong, there are bona fide audiophiles out there who know their stuff, but they are among the few and may be hard to identify, and the rest is typical forum chatter. One person mentions a trait he has conjured up for an amp; next thing you know, fifty-eleven members are arguing the same hearsay trait for that amp as pure fact, some not having even heard the amp, but they enjoy keeping the rumor mill going. It’s quite a mess, yet I occasionally find reading it entertaining. I also see conflicting comments on the same amp with professional reviewers and a vast list of adjectives describing differences; some contradicted between reviewers. Maybe it’s possible for both to be accurate in some of their assessments based on their environment. Some professional reviewers have superb listening capabilities, and they express it well. Then there are hundreds of wannabe professionals trying to make a living on YouTube, and the only credibility they have is with friends and forum members who like them and promote their channel. A few of them are legit and provide helpful, objective reviews with their reasonable subjective opinion. There is one thing for sure: there will never be a 100% consensus among everyone on how any given amp sounds, whether there is or is not a difference.
While my opinion is not chiseled in stone, I tend to lean towards the camp of being unable to identify any worthwhile audible differences in quality solid-state amps, which includes most good quality amps these days, provided they are not over-driven. I am NOT stating there are no audible differences, which also does not mean I am not hearing a difference. However, I cannot identify the differences, unlike some who are apparently able to do so. If someone points out something specific, maybe I could identify it, but put a blindfold on me and forget it… I’m done. Nonetheless, I have more or less gravitated to the mindset that I want to ensure that I’m not missing out on the best there is to offer (within a range of the best measured if possible), whether I can identify it in listening or not. That doesn’t make sense because if I can’t identify it, how do I know it’s the best? I don’t, but let me at least choose from among the best measured, and likely, I’ll have one that will allow me to hear all there is to hear in a good way. That way, I know nothing is hindering everything there is to hear besides my ears being able to identify it. Maybe some of it is psychological. I consider the objective measurements, the features, and the cosmetic factor and make a choice. The cost can come into consideration to some extent. I don’t mind spending money on something I want, and I have undoubtedly gone overboard if I desperately wanted something. I’ve spent some serious money on amps and stepped up on cables more than usual.
The following two sections will discuss hearing differences further. Rather than taking up space in the review not directed toward the actual headphone amp comparison, I have hidden these sections behind spoiler tags. Perhaps they might be of interest to you.
Something I read several years ago from Benchmark Media’s VP and chief designer John Siau’s application notes… some fascinating articles: https://benchmarkmedia.com/blogs/application_notes
The first paragraph of his Listening vs. Measuring article immediately caught my attention.
At Benchmark, listening is the final exam that determines if a design passes from engineering to production. When all the measurements show that a product is working flawlessly, we spend time listening for issues that may not have shown up on the test station. If we hear something, we go back and figure out how to measure what we heard. We then add this test to our arsenal of measurements.
It’s worth repeating… If we hear something, We go back and figure out how to measure what we heard.
If differences are heard, it makes sense that something in one or the other amp is causing the difference. It should be identifiable and measurable; at least, I would suggest so.
Here’s a quote from a professional reviewer that resonates with me… I then switched to Generic cable and instantly the sound was louder and there was better clarity all around! This effect quickly faded though in a few seconds indicating typical faulty sighted listening test effect.
I’ve experienced this same phenomenon. Too many people don’t recognize the fade effect because they are too enamored with the initial excitement. They hold on to it, claiming there is a difference when there actually isn’t. It’s truly classic.
I appreciate what Paul Seydor of Absolute Sound wrote in his review of the AHB2. Here are a few clips from his review. (Underlined emphasis by me.)
I don’t have much to say about the sonic qualities of Benchmark’s new AHB2 power amplifier because there isn’t that much to say. Used within its limitations and for its intended purposes it is in any practical sense perfect. I know this is not the sort of thing we’re supposed to say about products, but it has been evident for a very long time now that solid-state electronics, particularly linestage preamplifiers and power amplifiers, have reached a point where they are effectively a solved problem such that it is exceeding difficult to tell one from another even in the most exacting A/B comparisons. Ferretting out differences typically involves zeroing in on a very specific and limited characteristic or set of characteristics with such concentration as to leave one tired, uncertain, or both: in other words, an activity that is the very antithesis of what is involved in listening seriously, even critically—to say nothing of pleasurably—to music. [I must point out that the TAS editorial staff does not share this view. —RH]
That said, even by contemporary standards of the most sophisticated, exotic, and expensive electronics, this new amplifier is something of a technological tour de force.
As a remarkable number of audiophiles still tend to listen with their eyes rather than their ears, there continues to be a prejudice in favor of size, weight, and bulk, especially as regards speaker systems and amplifiers. I have no wish to engage the double-blind test debate here, but I do think there’s a lot to be said for not knowing what you’re listening to when evaluating components, particularly when it comes to electronics. The truth is that if electronics, particularly solid-state electronics, are correctly designed, they just work: When they don’t sound neutral the reason is typically some limitation or flaw in the design, being pushed beyond their rated power, an interaction with untoward speaker loads and/or cabling, or a flavor the designer consciously built into it (e.g., the exceptionally pretty Gundry dip Bob Carver designed into his Sunfire amplifiers).
https://www.theabsolutesound.com/articles/benchmark-ahb2-amplifier/
This, to me, is when honesty and reality are harmonized beautifully by a reviewer.
Kal Rubinson of Stereophile wrote the following in his review of the AHB2. (Again, underlined emphasis by me.)
Benchmark and THX make much of the AHB2's lack of audible noise: something good systems aren't troubled by in any case. That said, it was probably the AHB2's low noise level that revealed to me much more apparent low-level detail in already-familiar recordings. I qualify that statement with apparent because, after hearing the AHB2 uncover previously unheard subtle details, I found I could now hear them when I returned to my other amps. I suspect that, being newly informed of their existence, my ear/brain could more easily extract those details from the output provided all along by my other amplifiers. This made a much greater impression on me than any subjective awareness of a lower noise floor, per se.
https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier
The first paragraph of his Listening vs. Measuring article immediately caught my attention.
At Benchmark, listening is the final exam that determines if a design passes from engineering to production. When all the measurements show that a product is working flawlessly, we spend time listening for issues that may not have shown up on the test station. If we hear something, we go back and figure out how to measure what we heard. We then add this test to our arsenal of measurements.
It’s worth repeating… If we hear something, We go back and figure out how to measure what we heard.
If differences are heard, it makes sense that something in one or the other amp is causing the difference. It should be identifiable and measurable; at least, I would suggest so.
Here’s a quote from a professional reviewer that resonates with me… I then switched to Generic cable and instantly the sound was louder and there was better clarity all around! This effect quickly faded though in a few seconds indicating typical faulty sighted listening test effect.
I’ve experienced this same phenomenon. Too many people don’t recognize the fade effect because they are too enamored with the initial excitement. They hold on to it, claiming there is a difference when there actually isn’t. It’s truly classic.
I appreciate what Paul Seydor of Absolute Sound wrote in his review of the AHB2. Here are a few clips from his review. (Underlined emphasis by me.)
I don’t have much to say about the sonic qualities of Benchmark’s new AHB2 power amplifier because there isn’t that much to say. Used within its limitations and for its intended purposes it is in any practical sense perfect. I know this is not the sort of thing we’re supposed to say about products, but it has been evident for a very long time now that solid-state electronics, particularly linestage preamplifiers and power amplifiers, have reached a point where they are effectively a solved problem such that it is exceeding difficult to tell one from another even in the most exacting A/B comparisons. Ferretting out differences typically involves zeroing in on a very specific and limited characteristic or set of characteristics with such concentration as to leave one tired, uncertain, or both: in other words, an activity that is the very antithesis of what is involved in listening seriously, even critically—to say nothing of pleasurably—to music. [I must point out that the TAS editorial staff does not share this view. —RH]
That said, even by contemporary standards of the most sophisticated, exotic, and expensive electronics, this new amplifier is something of a technological tour de force.
As a remarkable number of audiophiles still tend to listen with their eyes rather than their ears, there continues to be a prejudice in favor of size, weight, and bulk, especially as regards speaker systems and amplifiers. I have no wish to engage the double-blind test debate here, but I do think there’s a lot to be said for not knowing what you’re listening to when evaluating components, particularly when it comes to electronics. The truth is that if electronics, particularly solid-state electronics, are correctly designed, they just work: When they don’t sound neutral the reason is typically some limitation or flaw in the design, being pushed beyond their rated power, an interaction with untoward speaker loads and/or cabling, or a flavor the designer consciously built into it (e.g., the exceptionally pretty Gundry dip Bob Carver designed into his Sunfire amplifiers).
https://www.theabsolutesound.com/articles/benchmark-ahb2-amplifier/
This, to me, is when honesty and reality are harmonized beautifully by a reviewer.
Kal Rubinson of Stereophile wrote the following in his review of the AHB2. (Again, underlined emphasis by me.)
Benchmark and THX make much of the AHB2's lack of audible noise: something good systems aren't troubled by in any case. That said, it was probably the AHB2's low noise level that revealed to me much more apparent low-level detail in already-familiar recordings. I qualify that statement with apparent because, after hearing the AHB2 uncover previously unheard subtle details, I found I could now hear them when I returned to my other amps. I suspect that, being newly informed of their existence, my ear/brain could more easily extract those details from the output provided all along by my other amplifiers. This made a much greater impression on me than any subjective awareness of a lower noise floor, per se.
https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier
Consider what Floyd Toole wrote in his book, Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (AES Presents) 3rd Edition.
In audio, there are numerous parallel examples of listeners hearing qualities in sounds that are not, or simply cannot, be there. If one believes that there will be a difference, there very likely will be a difference. The sound waves impinging on the eardrums have not changed, but the perceptual process of the brain has decided that there is a difference. Double-blind tests may show that there is no difference, but such is the strength of belief that some people argue that it is the test that is at fault, not the reality that no change in sound existed. Some audio journalists promote these ideas, and products possessing these mystical powers come and go.
Several amp comparison events have occurred over the years, including Richard Clark's infamous $10,000 challenge. It is reported that several thousand took the challenge, but no one ever won. Why? Several thousand claimed they could hear differences, but they failed when tested. How is it possible that not even one person could ever take the ten grand from Richard? Surely, at least some of these taking the challenge were among the discussion forum chatters.
https://web.archive.org/web/20130716171611/http://tom-morrow-land.com/tests/ampchall
We conducted an amp evaluation event at my home back in 2015, using eleven amps and the Van Alstine ABX Switch Box. We could not hear a difference with any majority consistency, and certainly not 100% that Richard would require to win the 10K. Any differences claimed to be heard were so subtle that they weren’t material to listening enjoyment.
https://www.avnirvana.com/threads/2015-amp-comparison-event.14107/
In 2019, the Hollywood Sapphire Group met for an AB amp test. About 50 audiophile members participated and were “dumbfounded” by what happened to them.
https://matrixhifi.com/contenedor_ppec_eng.htm
https://www.avnirvana.com/attachments/sapphire-meeting-story-2021-pdf.41737/
There have been several instances of those claiming blind AB testing is insufficient because, for various reasons, we need to live with the amp for several weeks before we can hear differences. However, there have been studies conducted that prove otherwise. Check out this AES article by David Clark: https://www.studocu.com/en-au/docum...ts/audio-production/audiotheory1-2019/9311919.
While Amir at Audio Science Review is well respected in some online communities, a few discussion forums have members who hate him. Please don’t take my word for it; search for his name on the various forums and read it yourself. The comments are disrespectful and downright mean. It’s truly unbelievable how some people can be so immature and childish. Amir provides an exemplary service to the audio community with his measurements, whether you like it or not. His efforts remind me of what Paul wrote to the Ephesians… And have no fellowship with the unfruitful works of darkness, but rather expose them (Eph. 5:11). Amir exposes the snake oil in the industry by way of his testing, and it holds manufacturers accountable for their claims. I don’t always agree with his subjective comments, but that holds true for any subjective comments in reviews or testing. We must listen and see if we like what we hear rather than take anyone else's word. I bring up Amir because he summarized David Clark’s article, which I believe was brilliant. AES Paper Digest: Sensitivity and Reliability of ABX Blind Testing https://www.audiosciencereview.com/...ity-and-reliability-of-abx-blind-testing.186/
True… this still does not 100% prove there are no differences, but it would seem to justify that the majority can’t hear differences. There may be other events that I’m not aware of. We all hear differently, as evidenced by what speakers and headphones we like. I could never trust what someone says about speakers or headphones, although it might cause me to try something I otherwise might not, to see if I like it. I’ve listened to speakers and headphones costing substantial money and praised by those praised for praising them. Yet, they did nothing for me. We all have our preferences. On the other hand, I’ve never owned an amp that I didn’t like because of how it sounded. I’ve never heard one that sounded better than the previous one in my system. Speakers and equalization have always made the most significant differences for me. I have had a receiver that ran out of juice at higher volumes with my MartinLogan electrostatic speakers, and I have had amps that were pushed almost to their limits (flashing LED warnings). Still, otherwise, they all sounded excellent, never hindering my listening… precisely what they were designed to do.
In audio, there are numerous parallel examples of listeners hearing qualities in sounds that are not, or simply cannot, be there. If one believes that there will be a difference, there very likely will be a difference. The sound waves impinging on the eardrums have not changed, but the perceptual process of the brain has decided that there is a difference. Double-blind tests may show that there is no difference, but such is the strength of belief that some people argue that it is the test that is at fault, not the reality that no change in sound existed. Some audio journalists promote these ideas, and products possessing these mystical powers come and go.
Several amp comparison events have occurred over the years, including Richard Clark's infamous $10,000 challenge. It is reported that several thousand took the challenge, but no one ever won. Why? Several thousand claimed they could hear differences, but they failed when tested. How is it possible that not even one person could ever take the ten grand from Richard? Surely, at least some of these taking the challenge were among the discussion forum chatters.
https://web.archive.org/web/20130716171611/http://tom-morrow-land.com/tests/ampchall
We conducted an amp evaluation event at my home back in 2015, using eleven amps and the Van Alstine ABX Switch Box. We could not hear a difference with any majority consistency, and certainly not 100% that Richard would require to win the 10K. Any differences claimed to be heard were so subtle that they weren’t material to listening enjoyment.
https://www.avnirvana.com/threads/2015-amp-comparison-event.14107/
In 2019, the Hollywood Sapphire Group met for an AB amp test. About 50 audiophile members participated and were “dumbfounded” by what happened to them.
https://matrixhifi.com/contenedor_ppec_eng.htm
https://www.avnirvana.com/attachments/sapphire-meeting-story-2021-pdf.41737/
There have been several instances of those claiming blind AB testing is insufficient because, for various reasons, we need to live with the amp for several weeks before we can hear differences. However, there have been studies conducted that prove otherwise. Check out this AES article by David Clark: https://www.studocu.com/en-au/docum...ts/audio-production/audiotheory1-2019/9311919.
While Amir at Audio Science Review is well respected in some online communities, a few discussion forums have members who hate him. Please don’t take my word for it; search for his name on the various forums and read it yourself. The comments are disrespectful and downright mean. It’s truly unbelievable how some people can be so immature and childish. Amir provides an exemplary service to the audio community with his measurements, whether you like it or not. His efforts remind me of what Paul wrote to the Ephesians… And have no fellowship with the unfruitful works of darkness, but rather expose them (Eph. 5:11). Amir exposes the snake oil in the industry by way of his testing, and it holds manufacturers accountable for their claims. I don’t always agree with his subjective comments, but that holds true for any subjective comments in reviews or testing. We must listen and see if we like what we hear rather than take anyone else's word. I bring up Amir because he summarized David Clark’s article, which I believe was brilliant. AES Paper Digest: Sensitivity and Reliability of ABX Blind Testing https://www.audiosciencereview.com/...ity-and-reliability-of-abx-blind-testing.186/
True… this still does not 100% prove there are no differences, but it would seem to justify that the majority can’t hear differences. There may be other events that I’m not aware of. We all hear differently, as evidenced by what speakers and headphones we like. I could never trust what someone says about speakers or headphones, although it might cause me to try something I otherwise might not, to see if I like it. I’ve listened to speakers and headphones costing substantial money and praised by those praised for praising them. Yet, they did nothing for me. We all have our preferences. On the other hand, I’ve never owned an amp that I didn’t like because of how it sounded. I’ve never heard one that sounded better than the previous one in my system. Speakers and equalization have always made the most significant differences for me. I have had a receiver that ran out of juice at higher volumes with my MartinLogan electrostatic speakers, and I have had amps that were pushed almost to their limits (flashing LED warnings). Still, otherwise, they all sounded excellent, never hindering my listening… precisely what they were designed to do.
Comparison Intentions
Why bother with my headphone amp testing? First, I’m looking for amps for a couple of rooms in the house, as I am doing a lot more headphone listening now that I am retired. Secondly, I want to know if I can hear any differences. Maybe they are different from traditional home amps and intentionally made to sound different (colored to some extent), and I want to know for myself if that is the case. And again, it will be a fun experiment for me. I’ve read many reviews claiming significant differences, and as previously alluded to, there are always forum chatters claiming one thing or another about the difference in headphone amps. Yes, I have doubts, but I still want to make sure. After all, listening to headphones is different than listening to speakers… maybe there are some differences I can pick up on because of the intimacy of headphones. It doesn't matter if anyone else can hear a difference, and it wouldn’t matter what they heard because of the numerous contradictory opinions, nor do they have my ears. Who would I believe between the two contradicting each other? It’s better to discard what anyone else has said, erase the biases that may have developed, and start listening. I want to know if I can hear a difference and what the difference is, good or bad. Then, try to figure out what is causing it and hopefully determine how to measure it.
Testing Method
This test is relatively simple. I’ll use a couple of switchers, one 6.35mm and another 4-pin XLR, to switch between two or more amps while listening to specific clips of songs and some listening sessions with my playlist. I have an optical splitter, so I can use one of a couple of streamers I have on hand to feed multiple amps simultaneously. I can also group Roon Ready streamers to play simultaneously if needed. I will level-match the volume of each amp using my EARS headphone rig by playing a 1kHz sinewave via Room EQ Wizards generator and then level-match with the REW SPL meter. I can also run sweeps of each amp and see if there are any level differences at other frequencies. Some will suggest the EARS system is inadequate because it does not align with the more expensive systems such as GRAS. However, it is sufficient for measuring levels and differences as long as the headphones are not disturbed between the measurements. The headphones used will be the HIFIMAN HE1000se. They have several hundred hours on them and are the best headphones I’ve ever heard, although I keep searching for better. No… I don’t believe all headphones sound the same, but some sound similar to my ears in my evaluations. I’ll listen to various tracks I am familiar with via Roon from Tidal, Qobuz, and our library of CDs transferred to our NAS server. These are all WAVE or FLAC files. The good thing about this test is it doesn’t have to be blind because I have no reason not to be brutally honest with myself. If there is a notable difference, I hope to measure it or conduct blind testing for a self-check. These comparisons will not be completed in one day. It will be a few minutes one day, a few hours the next, and a day or two skipped between listening sessions, coming back to the same round of amps to confirm over and over what I am hearing.
Equipment
- HIFIMAN HE1000se headphones (35 ohm / 96dB sensitivity / 8Hz-65kHz FR) $1699 https://www.amazon.com/HIFIMAN-Full...-Comfortable/dp/B07H7GSDYV?tag=avnirvana03-20
- Douk Audio ONE Little Bear MC635 6.35 TRS Audio Switcher
- Zynsonix Audio 4-pin XLR Balanced Audio Switcher
- LiNKFOR Digital Optical Audio Splitter
- miniDSP EARS rig with Room EQ Wizard (for level matching)
- Prism Sound dScope M1 Analyzer (frequency response comparisons – THD+N if needed)
- Cables (AudioQuest, Hart, and others that are good quality and neutral)
- Roon Nucleus One with PC to control Roon
- ifi SilentPower LAN iPurifier Pro
- Omada 10Gb/2.5Gb Home Network
- Asustor Flashstor 6 NAS
- WiiM Ultra Streamer/DAC $329 https://www.amazon.com/WiiM-Touchsc...st-Headphone/dp/B0D41YCLW8?tag=avnirvana03-20
- Matrix Audio mini-i Pro 4 Streamer/DAC/Amp $959 https://www.amazon.com/Matrix-Mini-I-Streamer-ES9039Q2M-Decoder/dp/B0CC1WJ7PP?tag=avnirvana03-20
- Eversolo DMP-A6 DAC Streamer $859 https://www.amazon.com/Eversolo-DMP...-Touchscreen/dp/B0C48P4TQT?tag=avnirvana03-20
- Topping DX9 DAC/Amp $1299 https://www.amazon.com/Topping-DX9-NFCA-Headphone-high-Performance/dp/B0CL6FFLL7?tag=avnirvana03-20
- S.M.S.L. DO400 DAC/Amp $499 https://www.amazon.com/DO400-Headph...XU316-Silver/dp/B0CFTHK7MX?tag=avnirvana03-20
- HIFIMAN Goldenwave Serenade DAC/Amp $999 https://bloomaudio.com/products/hifiman-goldenwave-serenade
- RME ADI-2 DAC FS DAC/Amp $1299 https://www.amazon.com/Ultra-fideli...ne-Amplifier/dp/B081CWQXGD?tag=avnirvana03-20
- Aune S17 Pro Class A Amp $699 https://www.amazon.com/Aune-Headpho...ete-Balanced/dp/B0CRYK9L2G?tag=avnirvana03-20
- JDS Labs Atom DAC 2/Atom Amp 2 $272.99 https://jdslabs.com/bundle/atom-2-bundle/
- iBasso DX180 DAP Streamer/DAC/Amp $499 https://bloomaudio.com/products/ibasso-dx180
Out of necessity, some of these amps have heavy hours on them, as I’ve been rotating them 24/7 on my headphones for several weeks. A couple of them have zero hours on them intentionally. I’m not one of those who believes in DAC or amplifier break-in. As previously stated, I think the amps should be neutrally transparent out of the box and never change the sound of what we should be hearing. I’m not convinced headphones need breaking in either, although manufacturers recommend it. Nonetheless, my HEKse sound the same today as they did several hundred hours ago. If they have changed, I have not noticed it.
Listening Comparisons: Round One
The first round will compare the RME ADI-2 DAC FS headphone amp with the Matrix Audio mini-i Pro 4 headphone amp. It will also compare the ESS ES9028Q2M DAC to the ESS ES9039Q2M DAC. The WiiM Ultra will feed the RME, while the Matrix will use its built-in streamer/DAC. The first round will contain information about how the comparisons are handled and what I will listen for.
WiiM Ultra - SNR: 121 dB (A-wt) / THD+N (1 kHz): 0.00018% (-115 dB) for 44.1k to 192k / FR curve: +/-0.05 dB
Fixed full volume via digital optical to the RME ADI-2 DAC FS.
RME ADI-2 DAC FS – ESS ES9028Q2M DAC
- Output: 6.3 mm TRS jack, unbalanced, stereo
- Output impedance: 0.1 Ohm
- Signal-to-noise ratio (SNR) @ +22 dBu: 120 dB RMS unweighted, 123 dBA
- Signal-to-noise ratio (SNR) @ +7 dBu: 118 dB RMS unweighted, 121 dBA
- Output level at 0 dBFS, High Power, load 100 Ohm or up: +22 dBu (10 V)
- Output level at 0 dBFS, Low Power, load 8 Ohm or up: +7 dBu (1.73 V)
- THD @ +18 dBu, 32 ohm load, 1.2 watts: -120 dB, 0.0001 %
- THD+N @ + 18 dBu, 32 Ohm Load: -114 dB, 0.0002 %
- THD @ +14 dBu, 16 Ohm load, 0.94 Watt: -110 dB, 0.0003 %
- Max power @ 0.001% THD: 1.5 W per channel
VS.
Matrix Audio mini-i Pro 4 – ESS ES9039Q2M DAC
- 6.35mm unbalanced
- SNR: 116dB A-weighting
- THD+N:<0.0005%@20Hz-20kHz 2VRMS
- Output Impedance:<11Ω
- Output Power: 1200mW@33Ω, 260mW@300Ω, 130mW@600Ω, 1%THD
- Gain: +14dB
In this first round, with the Matrix amp using its own DAC/streamer, I will have to swap them to determine whether it is one of the streamers or one of the amps, should I hear any differences.
The Frequency Response is flat for both units—line out and headphone out—within the audible frequency range (20Hz to 20kHz). I have compared the filters on several of these amps and cannot hear any differences. Perhaps because the filters only affect the frequency beyond what we can hear. We can also see that the filters do not affect the lower frequencies in any response graphs. Remember, you can click on the graphs to enlarge them.
Level matching may be difficult on some of these, as the volume controls are slightly different, but I got these two amps within 0.1 dB of each other at my preferred listening levels of about 88 dB and 78 dB. I needed two different listening levels due to the varying track levels. Frequency responses for both amps on the HEKse were practically identical at both levels (within 0.4 dB).
To begin the comparisons, I am listening to 5-10 seconds of several specific songs from my reference playlist, which are lossless tracks of varying resolution. These are mostly songs that I’ve been listening to in our evaluations over the last 15 years. Some are newer and fresher, but I’ve heard most of them in several systems for years. There are a few that I’ve just recently discovered that I’m including because I feel they have excellent detail.
I switch back and forth between the amps while playing the 5-10-second segment of the track over and over, listening to the following:
- Paying close attention to each specific instrument to determine if I can hear any differences in the timbre, texture, or decay in each instrument's sound. (Repeat for each instrument.)
- Does any instrument or sound seem softer, brighter, or harsher on one amp or the other?
- Are the instruments and vocals imaging the same between amps?
- Does the soundstage width or depth shift between amps?
- For sub-bass-heavy songs, can I feel the rumble with each amp?
- Does any amp have more impact or punch in the bass/mid-bass or lack anything compared to another?
- Are vocals the same, or does any amp exhibit a sharpness or sibilance?
- Are the exact details and clarity noted on all amps?
- If I notice something particular on a song, can I switch to another amp and still hear it?
- Is any distortion noticed in any amp?
- Does any amp have a quieter background noise?
Let’s begin the comparisons.
Hmmm… I immediately hear a difference in the first song when comparing the first two amps. Wow! This is a first. At the beginning of Fink’s Trouble’s What You’re In (from the live version 2012 – Wheels Turn Beneath My Feet – FLAC 44.1kHz 16bit), he slaps his guitar to create a kick drum simulation centered around 60Hz (known after measuring). The slap on the RME is more pronounced and has more resonance. Flipping back and forth, it is easily noticeable. How could this not have shown up in the FR measurements? Those measurements were with the sweeps generated from REW and sent through the USB cable. We are streaming via Ethernet but still using the same headphone outputs. I’m scratching my head. Surely, this would be measurable.
I measured the frequency using the song and REW’s RTA (30 averages). I notice that 60Hz is higher on the RME, but they are very close as we move up in frequencies above 100Hz and through the midrange. This is why the bass seems heavier on the RME, but the vocals are almost identical.
If I increase the Matrix volume level by 5 dB and remeasure both, the bass is almost level-matched. However, the midrange and vocals are louder on the Matrix, which makes the song sound louder when switching back and forth. You can easily see this in the RTA graph showing the 5 dB level increase in the Matrix measurement.
Let’s play full-range pink periodic noise recorded to a wave file in Roon.
The RME boosts the low-end 5 dB as if there is a low-shelf filter at 100Hz. This is where the issue lies. All the settings in the RME are the same for optical input and USB, so the difference doesn’t make sense. EQ is OFF everywhere in the RME, and the loudness setting is OFF.
What about the settings on the WiiM Ultra feeding the RME? I'm looking at the app on my phone for the first time. The EQ on the Ethernet input source is set to ON, with a 100Hz low-shelf filter. This is why we did not see it on the USB input, as the EQ was set to OFF for USB… and only set to ON for Ethernet. So, any streaming was getting a low-shelf boost. Now, the difference makes sense. Lo and behold, how can that be if this is a new unit? Surely, this is not WiiM’s default setting. I have not touched any of the settings on the WiiM Ultra, so I wonder if I may have received a returned unit from Amazon.
In one sense, you could say I proved I can tell a difference in amps. However, a filter helped me a bit.
Okay, so let’s measure the song and the pink noise file again.
It's very close… within 0.2 dB. Let’s listen to Fink and see if trouble’s still what we're in here.
Switching back and forth, there is zero difference. The 60Hz guitar slap sounds the same on both amps. Vocals are identical, and string plucks are perfectly matched. Switching back and forth through several other song segments and full songs, I cannot identify any difference between these amps. They both sound excellent with the HEKse headphones. As a side note, these amps featured the ESS ES9028Q2M DAC vs. the ESS ES9039Q2M DAC. There are no differences between the DACs. Thus, implementations of their respective DACs appear to be well done.
I thought it was reasonable to include the initial issue I experienced with the WiiM EQ being on. I could have easily skipped over this and started with a clean slate, but it serves as an example of how some comparisons may be different, and unless measured, we may never know exactly what was causing it.
Listening Comparisons: Round Two
Round two will keep the RME ADI-2 DAC FS headphone amp in the mix and add the Topping DX9 and the HIFIMAN Goldenwave Serenade headphone amps. The WiiM Ultra will continue to feed the three amps via optical output to optical input. This will also compare the ESS ES9028Q2M DAC with the Hymalaya Pro R2R DAC and the AKM AK4499EQ DAC.
WiiM Ultra - SNR: 121 dB (A-wt) / THD+N (1 kHz): 0.00018% (-115 dB) for 44.1k to 192k / FR curve: +/-0.05 dB
Fixed full volume via digital optical to all three amps.
RME ADI-2 DAC FS – ESS ES9028Q2M DAC
- Output: 6.3 mm TRS jack, unbalanced, stereo
- Output impedance: 0.1 Ohm
- Signal-to-noise ratio (SNR) @ +22 dBu: 120 dB RMS unweighted, 123 dBA
- Signal-to-noise ratio (SNR) @ +7 dBu: 118 dB RMS unweighted, 121 dBA
- Output level at 0 dBFS, High Power, load 100 Ohm or up: +22 dBu (10 V)
- Output level at 0 dBFS, Low Power, load 8 Ohm or up: +7 dBu (1.73 V)
- THD @ +18 dBu, 32-ohm load, 1.2 watts: -120 dB, 0.0001 %
- THD+N @ + 18 dBu, 32 Ohm Load: -114 dB, 0.0002 %
- THD @ +14 dBu, 16 Ohm load, 0.94 Watt: -110 dB, 0.0003 %
- Max power @ 0.001% THD: 1.5 W per channel
VS.
HIFIMAN Goldenwave Serenade – Hymalaya Pro R2R DAC
- Frequency Response: 20Hz-20KHz, ±0.1dB@1KHz
- THD+N: 0.0015%, -3dBFS@1KHz
- Signal to Noise Ratio: -110dB, 0dBFS@1KHz
- Channel Separation: -120dB, 0dBFS@1KHz
- DAC output level : 4.5V/XLR, 2.2V/RCA, 0dBFS@1KHz
- Headphone amplifier power output: THD+N<0.07% @1KHz,
- Balanced output: 4000mW@32Ω, 760mw@300Ω;
- Single-end output: 2800mW@32Ω, 510mW@300Ω
VS.
Topping DX9 – AKM AK4499EQ DAC
- THD+N@1kHz (SE/BAL): <0.00010% @Output=550mW (32Ω) | <0.00007% @Output=550mW (32Ω)
- Frequency Response (High/Low): 20Hz-20kHz (+0.3dB) / 20Hz-40kHz (+0.6dB)
- Output Level SE (Low/High): 12V peak / 24V peak
- Output Power (SE)
- 3300mW x2 @16Ω
- 2100mW x2 @32Ω
- 4250mW x2 @64Ω
- 1190mW x2 @64Ω
- 240mW x2 @300Ω
- Output Power (BAL)
- 10000mW x2 @16Ω
- 7080mW x2 @32Ω
- 4250mW x2 @64Ω
- 950mW x2 @300Ω
- 460mW x2 @600Ω
The frequency response is relatively flat on all three units in the audible range. The Serenade deviated at the extremes by 0.2 dB SPL.
All three levels matched to within 0.3 dB. The slight variation below 10Hz for the 78 dB level should not matter, as I do not notice any sub-bass at that level. The 88 dB level is where I begin to notice sub-bass rumble, and there is hardly any deviation in those measurements. I would expect to see some variations from round to round due to the slightly different placement of the headphones on the EARS rig. The Serenade will be aggravating to level match because it has no volume level indicator. Each time I change the volume level, it must be releveled. I appreciate a digital volume-level read-out because it gives me a reference.
Please see the details in Round One of what I am listening for. Again… no differences in what I’m hearing, even in the slightest, between these three headphone amps. It is remarkable how they all sound exactly the same. I was hoping I could pick up on some little minuscule difference, but it’s just not there. Maybe the next round.
Listening Comparisons: Round Three
In this round, we have the Serenade in the mix to continue as a reference, and we add the S.M.S.L DO400 DAC amp. The WiiM Ultra will be the preamp for both of these amps. We will also add the Aune S17 Pro, which will receive a signal from the Eversolo DMP-A6 DAC Streamer. This will compare the Serenade's Hymalaya Pro R2R DAC with the S.M.S.L ES9039MSPRO DAC and the dual ES9038Q2M DACs of the Eversolo feeding the Aune S17.
This round will also use the Zynsonix Audio 4-pin XLR Balanced Audio Switcher, with two of the 4-pin cables being generic and one a Hart cable. Bryan Fox of Zynsonix custom-built this switch for me. He has been highly praised for his custom-built switches and cables. The 4-pin XLR cables are not easy to find, but Hart had them in stock, and I ordered one so there would be at least one higher-quality cable in the mix. The Hart cable is connected to the Aune S17 amp. I also have the ifi SilentPower LAN iPurifier Pro in the loop on the Eversolo. Therefore, if I hear any differences in the Aune S17 amp, I’ll swap cables to determine if the cable is making a difference and swap the ifi SilentPower LAN iPurifier Pro to see if it could be making the difference.
WiiM Ultra - SNR: 121 dB (A-wt) / THD+N (1 kHz): 0.00018% (-115 dB) for 44.1k to 192k / FR curve: +/-0.05 dB
Fixed full volume via digital optical to all three amps.
HIFIMAN Goldenwave Serenade – Hymalaya Pro R2R DAC
- Frequency Response: 20Hz-20KHz, ±0.1dB@1KHz
- THD+N: 0.0015%, -3dBFS@1KHz
- Signal to Noise Ratio: -110dB, 0dBFS@1KHz
- Channel Separation: -120dB, 0dBFS@1KHz
- DAC output level : 4.5V/XLR, 2.2V/RCA, 0dBFS@1KHz
- Headphone amplifier power output: THD+N<0.07% @1KHz,
- Balanced output: 4000mW@32Ω, 760mw@300Ω;
- Single-end output: 2800mW@32Ω, 510mW@300Ω
VS.
S.M.S.L DO400 - ES9039MSPRO DAC
VS.
Eversolo DMP-A6 – FR - 20Hz~20KHz(±0. 15dB) / SNR: >128dB / THD+N: <0.00009%(-120 dB) @A-wt ES9038Q2M*2 DACs
Fixed full volume via XLR to the Aune S17 Pro amp.
Aune S17 Pro – Amp Only
- 6.35MM JACK HEADPHONE OUTPUT
- Freq Response: 20Hz - 80kHz (+/- 5dB)
- THD+N: < 0.00038% @1kHz
- SNR: > 115dB @600Ω
- Crosstalk: < -105dB @1kHz 600Ω
- BALANCED XLR HEADPHONE OUTPUT
- Freq Response: 20Hz - 80kHz (+/- 5dB)
- THD+N: < 0.00016% @1kHz
- SNR: > 116dB @600Ω
- Crosstalk: < -110dB @1kHz 600Ω
- G-L 6.35mm jack headphone output (Low Gain)
- 738mW @ 32Ω
- 250mW @ 100Ω
- 166mW @ 150Ω
- 100mW @ 250Ω
- 83mW @ 300Ω
- 53mW @ 470Ω
- 41mW @ 600Ω
- G-L Balanced headphone output (Low Gain)
- 2773mW @ 32Ω
- 968mW @ 100Ω
- 645mW @ 150Ω
- 388mW @ 250Ω
- 333mW @ 300Ω
- 212mW @ 470Ω
- 116mW @ 600Ω
- G-H 6.35mm jack headphone output (High Gain)
- 2020mW @ 32Ω
- 675mW @ 100Ω
- 453mW @ 150Ω
- 273mW @ 250Ω
- 228mW @ 300Ω
- 145mW @ 470Ω
- 114mW @ 600Ω
- G-H Balanced headphone output (High Gain)
- 7507mW @ 32Ω
- 2643mW @ 100Ω
- 1793mW @ 150Ω
- 1089mW @ 250Ω
- 908mW @ 300Ω
- 580mW @ 470Ω
- 453mW @ 600Ω
Frequency responses are flat on all amps within the audible range.
Levels matched to within 0.2 dB for low-level listening and within 0.1 dB for higher-level listening.
Please see the details in Round One of what I am listening for. Unfortunately, there is still not much to discuss here, as I hear no differences in these three amps. I thought I heard something different on a couple of song segments, but after attempting to replicate it, I could not. These amps have stunning sound qualities when connected to my HEKse headphones. One note about the Aune S17 is I could fry an egg on top of it… it was HOT! There are no evident sound quality differences between the WiiM Ultra and Eversolo DMP-A6. I prefer the Eversolo over the WiiM Ultra due to the larger screen. There would be no way to choose between the products I’ve compared thus far based on how they sound, as they all are excellent.
Listening Comparisons: Round Four (Final)
For this round, we’ll keep the S.M.S.L with its ES9039MSPRO DAC in the mix for our reference and add the iBasso DX180 DAP with its Quad (x4) Cirrus Logic CS43131 DACs along with the JDS Labs Atom DAC 2 + Atom Amp 2 bundle using the older ESS 9018K2M DAC. We’ll use the ONE Little Bear TRS switcher for these three. The Eversolo DMP-A6 will be the preamp for the S.M.S.L and JDS Labs amps. The iBasso DX180 will be via the PC USB port. The DMP-A6 and DX180 will be grouped on Roon to play simultaneously.
Eversolo DMP-A6 – FR - 20Hz~20KHz(±0. 15dB) / SNR: >128dB / THD+N: <0.00009%(-120 dB) @A-wt ES9038Q2M*2 DACs
Fixed full volume via digital optical to the S.M.S.L DO400 and the JDS Labs Atom DAC 2 / Atom AMP 2 combo.
VS.
JDS LABS Atom DAC 2 / Atom AMP 2 combo - ESS 9018K2M DAC
- Frequency Response, 20Hz-20kHz+/- 0.01dB
- SINAD @ 2VRMS, 1kHz120 dB
- SINAD @ 50mV, 1kHz93 dB
- SNR (20-20kHz)124 dB
- IMD SMPTE-97 dB
- Noise (20-20kHz)1.33 μV
- Crosstalk @ 10kHz (RCA Out)-101 dB
- Input Impedance10k Ω
- Output Impedance0.7 Ω
- Channel Balance< 0.6 dB
- Max Continuous Power @ 600Ω143 mW (9.28VRMS)
- Max Continuous Power @ 300Ω286 mW (9.27VRMS)
- Max Continuous Power @ 150Ω570 mW (9.25VRMS)
- Max Continuous Power @ 32Ω2.65 Watts (9.22VRMS = 26Vpp)
VS.
iBasso DX180 DAP - Quad (x4) Cirrus Logic CS43131 DACs
3.5mm SE Headphone Out:
- Max Output Level: 3Vrms
- Output Power: 281mW + 281mW@32Ω, THD＜0.1%
- Frequency Response: 10Hz~75kHz -1dB
- SNR: 127dB
- Dynamic Range: 127dB
- THD+N: -116dB (A-wt, 600Ω)
- Crosstalk: -118dB
- Noise Floor: <1.1μV (High Gain)
- Output Impedance: 0.6Ω
- Max Output Level: 6Vrms
* Low Gain: 4Vrms - Output Power: 690mW + 690mW @32Ω, THD+N＜0.1%
* Low Gain: 500mW + 500mW @32Ω) - Frequency Response: 10Hz~75kHz -1dB
- SNR: 133dB
- Dynamic Range: 133dB
- THD+N: -121dB (A-wt, 600Ω)
- Crosstalk: -144dB
- Noise Floor: <1.1μV (High Gain)
- Output Impedance: 1.1Ω
As expected, the frequency response of all three amps is flat in the audible range.
Levels matched to within 0.2 dB for both listening levels. The JDS Labs unit is like the Serenade in that neither has a volume display, thus requiring relevel matching when changing the volume.
Amazingly, the iBasso DX180 sounds as good as these other amps. The JDS Labs Atom 2 combo is a little over half the cost of the DX180 and the least expensive of all the amps tested, yet equally as good as the most expensive amp. The DX180 also contains our entire CD music library on its SD card and has Roon. The portability makes it an excellent option for around the house and on the road. The 4.4mm balanced headphone output provides ample power and sufficient headroom while listening to my HFM HEKse headphones or UM Mest MKII IEMs. Its portability could eliminate the need for an extra amp, but what fun would that be? An avid enthusiast like me needs multiple amps, even if there is not much of a justifiable reason short of want.
Conclusion
Ultimately, I cannot identify any differences in these amps, but that does not mean anyone won’t be able to, and perhaps some may hear something in one that they prefer over the other. Your pocketbook and your ears will help you decide. My only recommendation is to be honest about what you hear and do your best to use a controlled testing environment if possible. As for me… I enjoy comparing speakers and headphones more often, for which I know I can hear differences. Yet, this was still a fun comparison to ensure I was not missing out on anything, and I am confident I am not. I’ll keep the S.M.S.L as I like some of its Sound Color options for fun. I’ll keep the RME ADI-2 DAC FS mainly because I like its loudness feature for listening at lower volumes. The DX180 was already a house resident and will continue as a convenient portable DAP. I’m not crazy about the Serenade or the JDS Labs due to their lack of a digital volume display (picky – I know). The Topping has too much bling with the clear top, and it gets a little warm but not nearly as bad as the Aune S17 Pro, which is too hot to touch at times. In the end, it was the features that helped me choose the amps I wanted, not the sound. The End!
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, but it’s a high price to pay for something that won’t sound any better than my dongle-DAC and Schiit Heresy.
