I added a separate amp to my system and now I have a 60 hz hum. The hum disappers completey if I disconnect the front speaker pre-outs from my receiver to the HT bypass inputs on my pre-amp. I tried numerous different scenarios using different circuits, trying everything on the same dedicated circuit, different cables, unplugging everything, cheater plug, etc. Depending on what I did, I could increase the hum or lower the hum but never get rid of it entirely unless I either unplugged the RCA cable from my reciever to the HT bypass input on the pre-amp, or used a cheater plug on the new amp. Doing either of these would give me dead silence but of course I would like to use the HT bypass and I am not sure it's safe to run the amp with a cheater plug. I guess I was somewhat surprised that when I had all components connected to one power center on one dedicated circuit I still got a slight hum. Any ideas on how to fix this?