In reply to:
Also, when I change the bookshelf to the other amplifier chan, the problem follows the speaker that makes the anomoly. This basically proves that the problem is with the speaker, and not with the reciever.
I did the same thing when my M60s first arrived. I heard a buzzing noise in 2 woofers, different ones, on different speakers. Called Joe of course and he suggested i swap the speakers to eliminate the source/song as the cause. I did and then i swapped the drivers from speaker to speaker, again to be assured the sound was specific to the driver.
However, i did these tests with a well recorded song (Holly Cole Trio- I can see clearly now) at relatively low volumes (around 60dB) so i knew that such a buzzing noise should not be generated due to any issue (like power or distortion) other than the driver itself. As i mentioned though, this other song off the Grosse Point Blank soundtrack (the Pete Townshend E.Cola mix of "let my love open the door") causes odd sounds from 2 of my present woofers at around 70-75dB and up yet i know that my woofers are fine at lower volumes or with other music (at higher volumes).
There is just something about some notes in that recording that either hit a certain resonance or cause draw on the receiver or have/create distortion somehow, etc. that creates the noise in my M60s. The same thing can happen with test tones and although it seems like a driver may be faulty, it really is not.
All that aside, it does sound like your driver is faulty and certainly my previous post was not meant to insinuate you had done anything wrong with your testing but rather to point out some of the general erroneous conclusions that ppl can come to when 'testing' their home systems with seemingly 'sound' (pardon the pun), yet potentially damaging methodology .
