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 problems.  All was great.   But then the noise.  It first started when I hooked up an optical cable from my tv (kd-34xbr960 with cable card) to my receiver and enabled digital audio for my tv.

I have found out that if I disconnect the sub, the noise goes away.  I can listen to stereo and digital audio from my tv through my five speakers without the buzz.  But when I hook up the sub (with power on or off), I get the noise.  Is there something wrong with the sub?