Help, new amp causing "buzzing" in speakers


I just bought and installed a parasound 5-channel amp in my system. I am now getting a "buzzing" noise from all 5 speakers. there may be a low level hum also but the noise seems to be coming from the midrange/tweeters. I know its the amp cuz I rehooked my old amps(NAD)and the noise went away. the noise does NOT get louder when the volume is increased. with 2-channel music its not that big of a deal but with movies the buzzing from the rear speakers is VERY annoying.

Anyone got any ideas on the cause of this? why isn't it there with my old amps? I don't really want to buy an expensive AC conditioner since I never had this problem before. could the amp be defective?

thanks in advance!!
draggcj
Yep, try what Rmml said. I had the same problem and installed a cheater plug and the problem went away. In our new house we don't have the grounding problem, so it's probably the wiring in your house.
If you have a cable TV connection going to your setup, disconnect it to see if the problem goes away. I had this problem with a ground loop and cable.