The mic I was using was connected into the keyboard. That is what is so strange. Why would it work with a single cable connect, but not work with the double cable connect? When I disconnected one of the two cables at the keyboard the mic came through fine.

I already had an SM58 connected into the Bose and my wife was using that, and sang beautifully as always.

The only other things I have connected to the power strip at home are 2 Focal monitors and a Kurzweil SP4 (all of which were turned off). Anyway I noticed the hum with my setup in a Nursing Home, with a different power strip.

I tried connecting my iPhone into the RCA connectors and it played fine with no hum.

I'm beginning to wonder if the problem is in the keyboard outputs. I'm not out tomorrow so I'll set it all up at home again. First of all I am going to see if can set it up in the same way with a different PA system, and see if I get the same results. Then later call Bose.