I thought ground loop hum was audible through the speakers? I don't have that at all...it's just right from the amp. I've had the amp (and everything else) plugged into a Belkin surge protector, but I tried plugging the amp directly into the wall outlet and no change. The only connection I have with my satellite receiver to the preamp is via an optical connection. It's connected to the TV via HDMI. I guess I could try a 'cheater' plug on the amp to see if that's the cause. I'm leaning more toward it being he standing DC that's causing it at this point, as the hum/buzz is just at the amp.