Hi Myles,
Thanks for being there with much needed help.
My amp (Carvin Bellair 50 watt combo, all tube) has recently developed a 60 cycle hum. Could this be caused by the tubes, even though they don't look blue, or is it more likely to be my cable?
This amp does not have a ground switch, and the buzz is evident wherever it is plugged in.
Thanks again,
Dan