niemanc

I was looking at that first. So I systematically unplugged the individual speakers from the amps and the noise continued. My reason for eliminating the interference from light ballasts etc, is mainly that this is occurring in two different buildings with two different amps. The only place that the two systems connect is on the wall in switch closet. So I am ruling against the possibility that these two systems coincidentally have interference at the exact same time of origination. Unless there is something I am missing. I haven't yet had to (thankfully) deal with this portion of our network, as a newbie.

cn