So a few days ago, I noticed this odd noise in my house that seemed to happen at random, it sounds like something electrical shutting done, slightly high pitched. After scouring the room, I found it to be on of my rear surrounds. It sounds fine in movies and TV, it only makes the noise after the Amp is shut down, say 10 seconds or so after. I'm going to swap speakers around to see if it could be something else...anyone ever have this happen? My speaker on it's way out perhaps?