Is dirty power the culprit?

One of the most frustrating experiences I have with home audio is when one day the system sounds so wonderful you are convinced you do not need to change a thing in your system and are set for life. Then the following day or a couple of days later the system sounds like a collection of items purchased at toys are us.

All attempts at adjusting VTA or VTF or whatever you can think of is to no avail. I'm left with the only solution, shut the system down and wait for a better day.

It probably does not help that I live in a condominium near downtown Boston. I am certain there must be other audiophiles living in similar circumstances. How do you deal with this problem? Is it always a problem with electricity? I would appreciate your input.