I had the same problem with my Quicksilver amps.
When I called them they told me if I have them on a shelf to put a carpet under amps and that did fix the problem. It was a vibration causing the hum. Give that a try if it works then you can get something better like a set of isoblocks [cork block] and put them under the feet of your amps!
When I called them they told me if I have them on a shelf to put a carpet under amps and that did fix the problem. It was a vibration causing the hum. Give that a try if it works then you can get something better like a set of isoblocks [cork block] and put them under the feet of your amps!