ive been noticing a vibration relatrd noise coming from my amp intermittently. It is not an amplified noise (it doesn't come through the speakers.) the amp is a Odyssey Khartago++. It seems to happen after warmup. About a minute of buzzing then back to normal for hours or days. I've also left it on continuously as recommended, and it still happens occasionally. Now this may sound crazy but I've noticed that sound several times when someone is in the kitchen. When water is running! Maybe an appliance (garbage disposal in sink) or microwave is on the same line? Could that be possible? The buzz comes from the left rear of the unit.