OK.....first thing I surmised is that the hum that I noticed on the QS8's was also evident on the M60's but only from the tweeter. Next thing I tried was unplugging the cable from the wall. No affect - still hummed. The hum did not change with the volume control on the receiver. Next I unplugged the sub cable and the hum vanished. So I pulled the sub out and to my dismay the cable snagged on the tv stand and the input jack broke off the sub panel - completely off. I can stick it back on but....Would it do any good to super glue it back on?? Luckily (or maybe unluckily) I have replaced the amp several times and I remembered JC telling me the Input and Output Jacks were linked. I plugged the cable back into Output Jack and, Voila, the sub still worked but the hum was still there. Reading Alan's article, I removed the chassis ground screw and that killed the hum. So....Hum gone, input jack gone, Dimmer stays....
