Power Purpose

Stringreen - 
Not saying there isn't something of a more fundamental nature going on between the two outlets; on the other hand, I wonder if it could be something as mundane as wiping the plug blades via unplugging and plugging back in thereby providing an improved connection?

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.