Thank you for your replies, gentlemen - I appreciate the input:
Ehoehn - Interesting! I can't help but wonder if the hum is an idiosyncracy of the Clayton design, perhaps in their earlier renditions such as mine. Hopefully some other Clayton owners will respond and either support or refute this idea. I need to contact Mr. Shen at Clayton for his advice.
Jazzdude - suffice it to say I'm still on the steep part of the curve w/ this hobby (affliction :-) but have read enough posts here on the forum to initially conclude that I was dealing with a gound loop problem. As stated, I have lifted the grounds on the amps, but I'm sure I need to do more investigation in this area. As an aside, I also possess the Sim W5, and have heard it paired w/ the Thiels CS 2.3's in a friend's system - very nice indeed. I bet the addition of the Supratek has really placed your system's sound in the "way sweet" category! The W5 currently resides in its shipping box, awaiting duty as the mains workhorse in our HT sytem, once reassembled. I need to get off my duff, and substitute it into the 2 ch room in order to get another take on the AC delivery. However, I wonder if different components can simply respond differently to the power issue - dumb question I'm sure.
Jejell - DC offset, hmm - I've seen the term before but that's about it. I intend to do my homework over at AA - thanks for that suggestion! I have read a bit on the humbuster, but was hoping I wouldn't have to add anything between the wall and the amps. Less is more, as they say ... but maybe not.
Thanks again, guys ... regards, Tom