buzzing noise

I am get a buzzing (hum) noise from all my speakers. My setup is Sony STR5ES receiver, Sherbourn 1500A amp, and Energy Veritas speakers for front and center, with Pinnacle in the rear. I have done a significant amount of trouble shooting, and determined that the buzz happens when I connect the receiver to the amp. Without interconnects from the receiver to amp there is no buzz. With all the component interconnects disconnect there is still a buzz, and the buzz exists even if I unplug the receiver.

The noise level of the buzz changes. At times, it is very low and hardly noticeable. Other times it very evident.

Does any one have recommendations?

Try a three to two prong cheater plug. It is probably a ground loop problem. Good luck.