Pretty sure I've isolated the culprit. I think it's my int. tube amp. I shut off & unpluged each piece of gear one at a time including the digital cable where it comes into the house. Everything was dead silent until the int. tube amp is turned on. A friend of mine suggested running a ground wire from the amps ground screw to my cold water line in the laundry room. He said totally isolating the ground should solve the problem. I'll give it a shot this weekend. Anybody else have this problem & how did you solve it? If this ground doesn't work what else can I do. I do have a cheater plug on the amp & it does quiet it down quite a bit but I'm not happy using cheater plugs. Thanks in advance!!