2ch amp and HT receiver connected to same speakers

Thanks everyone for the helpful comments. Regarding the ground loop, I have all my equipment powered by the same dedicated circuit. I have also tried the Granite State Ground Control and a cheater plug with minimal effect. The only input to the HT receiver is my DVD player via HDMI. The HT receiver outputs to my Projector, also via HMDI, and to my 2ch preamp via RCA. Thanks for any other ideas!

Try this simple test. When you can hear the HUM, simply walk to the wall (no place else. It HAS to be at the wall) and unscrew the coax CABLE at its very entrance to the room. If the HUM stops, then it is your incoming cable not being grounded.

If it does not then you have your work cut out for U.

Summitav, are you saying that the CATV coax would cause a hum even if it is not connected to my HT receiver?

Process of elimination. But this is what makes our hobby so much fun right? Absolutely start with cable or satellite. If it is not cable or satellite kill all other breakers in the house except the one feeding your system. See if the ground loop is gone, if it is start turning each breaker on one by one to see if it comes back. If it comes back when you turn on a certain braker you've found your problem. If all breakers are off and you still have the ground loop I would start unhooking cables one at a time, until it goes away. It could be a faulty cable, certain component, who knows? A lot of possible causes. With time and patience you should be able to figure out. Good luck and let us know what you discover. Have fun!

If the co-ax is hooked up to anything that is hooked up to the speakers where you hear the hum, it could be the co-ax. Of course, it COULD also be a bad cable somewhere in the system as well.

Install banana plugs on your cables for a quick disconnect when you switch between systems. Never run with both connected at the same time.