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!!
Try using a cheater plug, most of the time that is the cause of the hum.
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.
I've had this same problem with Parasound and Adcom amps, and using a cheater plug(floating the ground) will solve your problem.
Call Tony Pointes at 415-397-7100 as he is the head technician at Parasound and can likely get to the root of the problem.....
~~~~If this is the "B" Series 5 Channel Amp, Definately Call Parasound!

Calling Parasound is the best advice. Second if you have cable tv try a cheap filter. Third Plug amp into an outlet that is on a different circuit than what you have it in now.
I installed the cheater plug and it fixed the problem. All my other components (including old amps) only have a 2-prong plug, minus the ground. Why do they even put a ground on the cords if they cause this problem?

is there any negative to using one of these cheater plugs?

thanks again!
Plugs are grounded to avoid manslaughter charges when the electronics short out inside the component, you touch the unit, and the total output of the Hoover Dam momentarily passes through you on its way to ground. While it's not really that dramatic, next time you're out take a look at the footwear of the musicians down at the local hotspot. They know the benefits of rubber soles.
Manufacturers who stuff digital processors into their units are particularly adamant about using the ground, but the units seem to work ok without it. If it helps, audio hobbyists commonly believe that if one component is properly grounded, the rest of them will be too through the interconnects.