I recently replaced my mission front speakers with another pair of Kef 9000ACE's and after doing so have noticed everytime i switch my amp on or change sound mode (i.e. stereo to PLII) the sub makes what i can only describe as a huge bass thump noise. I have tried redoing the auto acoustic calibration but am still having the problem? :-( I even tried reconnecting the old missions back up but nothing. Any ideas anyone??? Cheers.