Thanks Leon for your input.

I've since returned my hook-up arangement to the way I had it before and have not had any problems. I believe the main issue was hooking up my sub via the high level connections. It must've overloaded the amp or something.

I went back to using the line level sub out to the sub's lfe input. I can easily crank the receiver to 0dB with no drop outs of power at all.

I must say my feelings have been mixed as well. But these aren't simple heathkits either.
And now that my receiver is working well I have no issue. I might add the amp section is incredibly dynamic and really does sound fantastic. Particularly with the ending gun fight scene in Open Range.