Viggen has the right idea. Keep in mind all transformers hum to some degree. Some manufacturers pott them to reduce hum but that only creates a new set of problems.
Does anyone have similar problem with Pass Amp?
I'm just wondering if what i'm experiencing is normal. I have a Pass X250 and Pass X1. When my preamp is muted or turned off I get a slight hum from the right speaker. The hum is only audible when the room is dead silent and my ear is right up against the speaker. Obviously it's not a major issue however i do not hear any home from the left speaker. Is this slight residual hum from right channel only normal? Any input would be appreciated. Thanks