To date, I have been using my AVR300 in stereo mode to listen to DVD movies, CDs and over-the-air television. With this set-up, both front speakers and the subwoofer work great. This weekend, I brought home a center speaker and a pair of surround speakers for audition. Cable/over-the-air television broadcasts in Dolby 5.1 are terrific, with all speakers working perfectly. When I listen to DVDs, CDs and SACDs in stereo mode, the front speakers and subwoofer work just fine. However, when I try to watch a DVD or listen to an SACD, there is no sound coming out of the subwoofer. BTW, my DVD/SACD/CD player is a Sony DVP NS-900V. Any thoughts on what is wrong would be greatly appreciated. Thanks, in advance.