Best thing to do first to be sure it is the Cary is to disconnect all components from it and plug it into the wall (if you have done this already my apologies). Is the hum still there? If yes then it is the Cary, if no, something further up the chain is causing it. Add one component at a time starting with the PS Audio until the hum appears. Cheater plugs are great for diagnosing the problem. You'll read all sorts of stuff here about the positives and negatives of their use on a permanent basis. I don't like them as a rule but sometimes you may just have to live with them, or get a balanced power conditioner.
Buzz/Hum from Cary SLI-80
When I turn on my Cary, a electronic hum is immediately audible. It does not increase in volume when I increase the volume control. It is not loud, but distinct. When I turn on the CD player, the hum remains. When I play a CThe hum is present in either Triode or UL mode. The Cary is plugged into a PS Audio UPC 200, which is plugged into silver outlet in wall. This is not a big problem, but shouldn't it be dead silent when I turn on the Cary? Could it be the tubes? Any suggestions welcome. Thanks