C1000a

I have a C1000a and for the most part it works great. Occasionally, we hear a hum coming from all 5 speakers hooked up. We shut the unit off and it goes away for a while and comes back. Sometimes we won't hear it for weeks at a time. Is this a grounding issue or what?

This might be hard to figure out.

Do you have it on a power conditioner? Is there another outlet on a seperate breaker you can try? I would also note in a log what appliances are on and running. Note which components you have turned on and what ones are in stand by.

I think someone also had an issue with dimmer switches that caused some strange issues.

Unplug your cable connection & see if it goes away....