I have a CE2000 amp and there is a constant buzzing noise that comes from the speakers. The buzzing noise is not a ground fault, and the noise occurs even without any inputs connected. One channel buzzes louder then the other (channel 1 is the louder of the two) and adjusting the volume on the amp doesnt change the buzz at all. If I run the amp with a source connected, once the amp heats up the buzz becomes progressivly louder and louder, changing pitch as the fan speed changes. When the fan stops the buzzing quiets down a bit (but its still there). Once the amp is running for a bit the buzz can actually be heard over the music. Any idea what could cause this?