@knittersspouse- I found your post informative. Can you focus on the OP's use of power regenerators? That is, devices like the PS Audio boxes that are akin to amplifiers and take power from the wall receptacle but then "regenerate" it?
The impression is that these devices are immune to the changes that happen on the power line (or upstream on the grid) feeding into one's home. That's what the OP is puzzled by-- that despite his use of these regenerators, he hears different sound quality at different times.