When you have a DD 5.1 or DTS track, the 1050 disables the DSP modes (natural, stadium, jazz...) and outputs the surround sound as recorded. You can still use stereo, 3channel or phantom modes as these compensate for lack of speakers in the missing positions. If you really want to use the DSP modes, you can use the analog 2-channel output from your DVD. But why you would want to do that is beyond me.