We agree on the importance of dedicated lines as I also have two 20 amp dedicated lines into my music room. This should be first and aftermarket cords second. I was stunned at the difference power cords make as I tried various ones in my system. Each of them highly regarded, but changing the overall sound in some cases. I have settled on heavy gauge, solid core copper on all my wire. Multiple runs of heavy gauge! solid core is very stiff and a pain to deal with, but sounds right to me.
Well, I have changed out out power supply caps in a past Sunfire Signature SS amp and had them upgraded in an old Hafler amp and both realized nice improvements. You have much more knowledge on technical matters then I do, so what you say may be true in many cases.