Say What?
Nature has a noise floor?
Man made noise floors are better?
Most amplifiers have only a -30 to -35db noise floor?
That would sure put a limitation on dynamic range.
-75 db relative to your 2.8 volt reference would be 500uV, certainly attainable. You were off by three decimal places.
A power cord can affect both voltage and current.
Using a to small of conductor can restrict both.
Phase angle AKA power factor is caused by a reactive load as opposed to a purely resistive load. The reactive component of the load determines the amount of voltage vs current phase shift. Not the size of the load.
And while the theory of filters is simple, the application can be far more difficult, though sometimes you can luck out and solve a problem with one $2 capacitor.
But I do agree with your main point, that better sound from a power cable is most likely psychological.

Quote:
Say What?

But I do agree with your main point, that better sound from a power cable is most likely psychological.

I like that statement. Paying $100 for a $5 power cable would be insane for only an insane buyer would do that. Sort of reminds me of Milo Minderbinder making chocolate covered cotton balls and trying to serve them in the mess hall. It was Yossarian that gave Milo the idea of selling them to the government.