For starters i would say it's in your best interest to protect your expensive gear with a good surge protector, one that is better than your average household one. I also just installed a power conditioner/surge protector that cost $500.00 in my studio. Before i bought it i would have to unplug the fridge that was in the waiting room whenever i was recording, Becuase i was getting Pops everytime it kicked on. The conditioner now filters that, which i assume it filters any stray spikes and electrical abnormalities. I think the worst thing is when you have a client recording at your studio doing takes, and rite in the middle of a good vocal track you hear POP!. If i knew what i know now when i started buying gear that probably would have been one of the first things on my list.

Hi

Power supply certainly affects audio quality. "Brown outs" where the voltage from the mains dips, can reduce audio quality. Also, the set up of your individual power supply units can affect things------the best hi fi systems for example have separate power supply units so as to not affect the electronics in the amps and preamps with the electromagnetic fields. Treat yourself and have a listen to some top quality stuff like the Naim amps and preamps, and you'll be amazed by the difference in sound quality between integrated amps, to separate amps and preamps, to separate amps, preamps and powersupply units....

Are we talking about the computer's power supply or the power supply to the computer?