Even Denon can't figure this one out ! I recently added a Rotel 5ch power amp as an upgrade to my system. Since day one, the pre-outs from my Denon are creating a loud hum in all 5 channels of the amp, even without ANY inputs connected to the pre-pro. With only a single channel connected at a time or all five, the humming level simply increases accordingly. I seem to have tried everything from different interconnects, same or separate outlets (I have three dedicated outlets in the theater room), different speaker, line conditioner, etc...same results. The sub-out does not create this hum thru my PSB sub though, and it's part of the same circuit board as the other pre-outs. Go figure ??? Any ideas to fix this ? By the way, the power amp was tried with another pre-pro and checked by Rotel tech and everything works just fine.