Hi Grayson,
I think the short answer to your question is yes, a properly designed power supply will filter noise from the incoming AC.
The idea behind power conditioners is somewhat different than the PS Audio Power Regenerator. Power conditioners isolate, filter and regulate to some degree but big voltage swings can not be compensated for normally. They are also supposed to provide protection from voltage surges like lightning strikes. But a power conditioner only passes the same AC given to it albeit through a transformer (sometimes) and filtered with circuitry designed to pass anything above 60 hz to ground. Effectiveness always depends on design implementation of course!
The PS Audio Power Regenerator literally changes the incoming AC to DC (nothing quieter than DC after All) and then converts it back to, according to the claims, a pure AC sine wave.
https://www.psaudio.com/perfectwave-p5-power-plant/
My only issue with this scheme is the cost and the possibility of current regulation restricting the potential of the amps.
If your dealer were confident enough to arrange a demo featuring the same amp with the PS Audio device and without to demonstrate the difference I would be much more willing to buy into his claim. Or loan you the unit for a trial perhaps.....?
It is my strong opinion that while power conditioning and certainly power surge protection may have a value... The power supplies in modern well designed equipment is well up to the task.
Where we run into noise issues in this world of ours is the RF saturated environment we live in and the ground loops we inject into our own systems.
If as Tony said you can’t hear any noise when you turn on your system to a unused (no signal) input then a power conditioner is unlikely to improve anything. If noise is clearly audible during moments of silence then it is time track down the noise maker.
If you have “inky black” backgrounds already or hear no noise unless you ear is buried in your speaker no power conditioner or power regenerator or $10,000 power cord is going to improve your sound or “lift any veils”!
That’s my two cents worth.
Tom