First try to find the source. What inputs are you using? If you have a cable box, DVD player and/or other sources, try each one independently to see if they all buzz. If they do, are your connections close to your wall plug(s) or other source(s)/connection(s)? Give each interconnect and speaker wire independent space to see if any of them are picking up interference. And start with the bare minimum, testing at each step. Sometimes a little reverse engineering can help discover the problem. But if none of this works, unplug your receiver, grab your dvd player and a speaker and create a simple stereo setup in another room. If you're still hearing a buzz, then yes, it's likely your receiver.