DTS will often, on DVD's, have a bitrate of around 1.5 Mb/sec. DD maxes out at 640 or 750 Kb/sec for a bitrate, so the DTS will have less compression then, if it was mixed well. This is why on some of the DTS DVD's that Universal used to put out (Out of Sight, Jaws, etc...) they didn't have the special features of the standard discs since they were using that room for the DTS soundtrack.