As Sanjay pointed out, DTS is an audio format similar to Dolby Digital. DVD's that have DTS tracks generally also have a Dolby Digital track that is the default, so you first need to go into the disc's audio or setup menu (whatever that particular movie calls it) and change the audio from Dolby Digital to DTS. It may prompt you to confirm that you really want DTS, since not all receivers support DTS (mainly older gear). Once that is done and you start the movie, the Sherwood should detect the presence of a DTS source and automatically switch to it with no effort on your part.