I wonder what the buzzing is doing to the sound field in the room??
I think it is logical to assume it would be messing with the sound field that was set up using SPL, YPAO or Audyssy
61/81+db at the screen down to 41+db 11/12ft away IMHO might be capable of doing just that?
Therefore, redoing the sound calibrations with the set on would be warranted