I can speak from experience about the effects of the quality of the power on the performance of your gear.
Back in the late 1990's I moved into a brand new home, but in an older subdivision.
I had Quad 63 and Meitner mono block power amps.
During my first summer my amps shut down.
I sent them to Ed,he fixed them, sent them back, and in the next day or so, they shut down again.
He said there was nothing wrong with the amps, and that I should consult my power provider.
To make a long story short,a new transformer was attached to the pole and I never had another issue with the amps shutting down.
The sound also improved,things opened up, it was faster,more detail, all the good stuff.
It was around this time that I replaced my power cords going to the Quads with DIY made from 12 guage Romex.
How much of an improvement was that?
The fellow who bought my Quads asked if the DIY power cords were also for sale.
It was ten years later or more that a friend of mine got into balanced power and upgraded power cords and dedicated lines.
I heard what they did to improve his sound which was already much better than mine, and much more expensive.
His system did things that mine was incapable of doing.
It got out of the way of the music.
I've since implimented many of his power upgrades and added a few others like designer fuses to the mix.
The results are that eventhough I have a complete system that doesn't cost as much as his Scarlatti digital set up does, I have narrowed the performance gap .
For me I don't wonder why or how this should be, it is what it is.