Help with room setup and sub integration - Reference quality 2-Channel?

[MediumRare]

Hey folks, I'm hoping to get your help on finishing the setup of my room. Here's what I working with:
- McIntosh MA6900: 200-400 WPC integrated amp with 5 EQ knobs (low Q @ 30, 150, 500, 1500, 10k Hz)
- B&W 804 Nautilus speakers (good down to 42Hz)
- 2 Rythmik F12 subs

Before setting up anything I tried a lot of REW Room Sim options, which essentially did work out IRL and have ended up with the layout below. (The room is approximately 24'10" x 17'1", with an 8'8" ceiling and carpeted floor. It's not exactly accurate, as the left wall has two different depth sections, with a hallway opening in the center; what is shown is as if it's all one dimension). The cones of the mains are 20" from the front wall, any more and they risk being knocked over. They are 7'10" apart and there's a flatscreen TV in-between, but above the tweeter level. The mains face straight ahead, so in a way that isn't so different from 60 degrees but then with each being toed-in 7.5 degrees. There is a large coffee table in front of the PLP and I did the measurements with a heavy blanket over it.

I had wanted the mains wider to get a 60 degree equilateral triangle, but I needed to bring the mains closer together and push the PLP back as far as possible to optimize the room modes, especially LF and the 128 Hz suckout. I played quite a bit with the subs' individual phase/delay and crossovers (and on one sub I used the onboard PEQ) to optimize the FR graph and minimize distortion. This is absolutely the best I could do on my own to the fix the suckout at 128 Hz; part of the solution is using +4 dB EQ on my 150 Hz knob. This is the result:

To be honest, listening to music it sounds pretty good to me. The soundstage is massive, with pinpoint accuracy horizontally and vertically, and the bass is very tight and big, to my ear - I tried various demo tracks to check all that. (Unfortunately I've lost any hearing above 14k Hz and, when I'm playing loud (like 100 dB) I have some LF resonances from furniture I can't get rid of .)

BUT: then I tried some bass test tones and found there are loads of audible phase and SPL differences in the LF which make me second-guess myself. So.... here we are. What do you think I can/should do?

REW mdat file is attached.

Thanks!

 

[ddude003]

If this is primarily a stereo system for music, and your mains go down to 42Hz, I would cross over your subs at ~52Hz +/-7Hz...
You might look for other places to move your subs to... Sub 1 to the left a bit more? And sub 2 farther down the right wall?
I would even be tempted to toe in your mains so they cross behind the Main Listening Position by a foot or two... And time aline them...
PS - Best to measure Left only, Right only, Sub1 only and Sub2 only...

 

[MediumRare]

If this is primarily a stereo system for music, and your mains go down to 42Hz, I would cross over your subs at ~52Hz +/-7Hz...
You might look for other places to move your subs to... Sub 1 to the left a bit more? And sub 2 farther down the right wall?
I would even be tempted to toe in your mains so they cross behind the Main Listening Position by a foot or two... And time aline them...
PS - Best to measure Left only, Right only, Sub1 only and Sub2 only...

Thanks! Subs are crossed at 50 Hz, which was the sweet spot for smooth FR (tried plenty of alternatives). I did play around with the sub locations: Moved the left one a foot to the left; moved the right a foot in either direction (after giving up on having the right sub near the right main - all were worse. Tell me what you have in mind regarding toe-in and how would I time-align (or even check the current time alignment, since the sub on the right did have its phase/delay adjusted)?

Regarding measuring one at a time, I did do the subs one at a time and also with and without the mains to see what were room modes and what was phase cancellation. The two subs are substantially different from each other! Did you have something else in mind?

 

[sm52]

Regarding measuring one at a time

To correctly configure the system, you need measurements of each participant separately from the rest. In this case, measurements should be with acoustic synchronization according to some chosen speakers. For example, according to the main right. Or on the main left. But not a sab. As a result, you should have 4 measurements. After that, you need to watch how they are friends with each other.
This is not a quick process. But in the screenshot of post #1, everything looks decent. So you can leave it.