It's a bit of both for me, actually. I can hear a hum from the amp itself, which appears to be...well..."amplified" in my speakers. It's sometimes louder in one speaker and sometimes about the same level in all speakers. Once I solved the fluorescent bulb thing, it went down to a level I can ignore during music or movies, but it gives me a metaphorical and sometimes physical headache knowing it's there. During my troubleshooting, I noticed that the only time I don't hear the buzzing from the amp and speakers is when NONE of my other electronics on that circuit are plugged in (including the receiver) and the amp is plugged into my Panamax power conditioner. Plugged into the wall, I hear the hum. Plugged into an outlet on a different circuit, I hear the hum. Plugged back into the Panamax, hum goes away (makes me feel a bit better about dropping that money for the conditioner). But of course the very next thing to plug back in is the receiver, and the hum comes back, whether the receiver is plugged into the wall or the Panamax (although I haven't tried the amp and receiver on separate circuits).

My thoughts as well, but I was on a roll so I threw that question in there too. I'm hopeful that the pre/pro (Onkyo PR-SC885) won't exhibit these issues, but I probably won't get my hands on that until January.

Thanks for the feedback.
-Brad