I recently took my HK AVR630 to an HK service center after the front left channel suddenly went quiet. Not silent, but very quiet. They've fixed it under warranty (big sigh of relief there) and called me to say it was done. I asked the guy on the phone what was wrong with it and he said that they 'did a factory adjustment and rewound the bias'. We both had about as much idea as each other as to what a 'Bias' is or how one might 'rewind', or possibly 'rewire', such a thing. Can anybody translate?