This may sound a little weird, but I'm having the most bizarre issue with my surround speakers. Just to let you know what I have:
5 Bookshelf Athena Speakers
Denon AVR-1612 5.1 Surround Amp
I recently moved into a new apartment, and I noticed that the speakers were making a low buzzing noise when the receiver was turned off (no buzz when it was turned on). So I unplugged the receiver from the surge protector. The buzz still persisted. So I unplugged the speaker wire from the speaker. And the buzz still existed.
So now I discover that each of my five speakers will make a buzzing noise along the inner wall of my apartment without any speaker wire or other cables attached!! It is very quiet, you have to put your ear next to the speaker. But if I carry the speaker and walk away from the wall, it slowly disappears.
What kind of interference from my wall could be powerful enough to make my speakers buzz when they are not even connected to anything? Should this be something I need to be concerned about?