Sorry, you are conflating issues. First of all, yes, you are right, one of the major improvements in components is how it address power. This is one of the keys to great sounding components… correct. But the more the more better. For instance, I added a $9,000 power supply to a $9,000 DAC (Sim Moon. 650D adding the 820 dedicated power supply)… big difference. This is why flagship components are frequently two box components, with one remote box dedicated to just the power supply.
A really good power conditioner, and direct lines I have put in have significantly improved my sound quality above that.
A power amp has different requirements. It needs unconstricted current or it is going to loose dynamics. So, most of us with high end systems use a direct line to the amplifier with no power conditioner and use a power conditioner for our other components… lowering the noise floor… by the way, something you do not hear directly. It takes experience to understand what a noise floor “sounds like”… you don’t hear it. It is the blackness in the background.. the comforting silence that makes you relax and fall into the comfort of nothing.