JB I had a driver go bad on one of my 80s not too terribly long after purchasing them and I located the bad driver by playing music while placing my ear within an inch or so to each driver until the culprit was found...you won't need to turn the volume up loud in order to locate a bad driver in this manner. You should definitely tell a discernible difference between the good drivers and the bad driver, if that is indeed the problem.

Other than maybe some sort of digital processing issue within the receiver in a particular mode (DD, PLIIx, DTS...etc) I wouldn't know what the cause may be.

Someone with a lot more knowledge than me will show up sooner or later, good luck!

Rick
Our Room

smile