Power Purpose

Could also be the wiring to the duplex. The old one may have loose connections, it may have been old and a lot of internal corrosion. The new one might have cleaner tighter connections internally. The old one may have had a lot of noise on the AC line, and the new one does not. And yes even unplugging then repugging the plug can clean off the tarnish enough to make a difference.

When was the last time you cleaned your contacts? People clean so infrequently that sometimes even just the cleaning action of unplugging and plugging cleans things resulting in better sound.

try 240 next time

Maybe it just is.  

""" ...just fooling around a bit.....plugged my power amp into a different outlet......boy ...so much better. """""


Just learned about this from Paul McGowan @ PS Audio. If both outlets do not share the same circuit breaker?If one outlet has electronic devices working on the same line they can dirty up the sound. If the better sounding outlet has nothing else sharing that line? It could make it behave like a dedicated line.