I'm getting a buzz noise from my speakers.  I have the 5.1 522 bookshelfls with the s-12 sub, a denon avr-3805 and a denon dvd-1910. The system was working fine ... I played my xbox, dvd (music and video, tuner and tv.  So I was playing stereo (through tuner and tv) and digital audio (through dvd and xbox) with no ...