Definitely not the sound of silence :

I turned on my Belles 150 amp today after being out of town for a while, and I immediately heard a high pitched oscillation accompanied by a buzz coming out of my speakers. I turned all other components off, and the noise persisted.

Any ideas what it might be? I turned almost everything off in the room and I still heard the sound.

I'm going to try another amp to see if that fixes the problem.