I'm a complete noob when it comes to surround sound, but I think this is a problem. I have a 5.1, 1000 watt home theatre in a box surround sound system rated for DTS and all dolby. When I turn on the system and play only 2.0, dolby digital 5.1, and all channel stereo i get a continuous high tone from the base and speakers. But when I play DTS tracks the tone is gone and it plays to perfection(at least to my ears) . What could be causing it?