Thanks for the replies!
I agree, I think it has something to do with my speakers. It just seemed odd that it was happening with the center channel and with one of the surrounds connected to the center channel output.
I had said that it happens rather randomly, however, it is consistent (makes sense right?
). What I mean is, I noticed a particularly bad case while watching digital cable and after DVR'ing the show the problem was most definitely consistent in that recording. Even the "peaks" and "troughs" of the ringing remained the same.
I will say that I am noticing it less and less as time goes on, whether the speakers are "breaking-in" as they say, or I'm becoming a conformist. Either way, my wife doesn't hear it, and when she's happy I'm happy
Sorry to go a bit off-topic guys. So, to remedy that a bit: that last night we watched the Blood Diamond Blu-ray, and I was extremely impressed with the spacial conformity and sound clarity that MCACC has provided! I have very, very little experience with audio, but our current home theater room must be an acoustical nightmare (fairly large, mostly bare walls, hardwood floor, one open side) and I have never heard such amazing sound. Plus, so far I've only run the default auto calibration as I haven't had time to follow the excellent guide at the beginning of this thread, but I can't wait to do a bit more tweaking when the opportunity arises.
Many thanks to everyone in this forum, I couldn't have gotten this far without the great advice in here! (and +1 to Macfan)