I have a buzz

Howdy, I recently began to put together a better two channel system. I had a Cambridge Audio 840a that I really liked. Then I moved up a bit to the Musical Fidelity A5.5. And here's the thing. Neither produced any buzz. Well... I had heard the Cambridge 840w and 840e and loved them and really wanted separates. When I had a chance to get them I did. So I hook them up and the amp is producing a very slight buzz through my speakers (I alternate between a pair of modded Klipsch Chorus and Klipsch RF-83.) I disconnected the preamp and the buzz was still there. I tried reconnecting everything and the buzz is still there. I even turned all of the lights in the area off and on and it didn't make a difference. And by the way, I don't have cable. So I have two questions:

1) What might I do to fix this? (Could a power conditioner make a difference?)
2) Can it harm my gear?

Thanks for the help.