My 7700 is on the bottom shelf of my two shelf high rack. I listened again last night. With my ear as close to the front of the amp as I could get, I could not hear any noise (hum or otherwise). I have 2 dedicated circuits but I don't remember exactly which way I plugged everything in. I think the subs are on one circuit (1000 watts rms each) and everything else is on the other. The satellite receiver and/or the PSP3 may be on the sub amp circuit - I don't think it matters for this discussion.