Well, does your player really have a DTS decoder or does it just pass the signal? As far as I know the only one with a DTS decoder built-in is the Panasonic A320.

One other thing is that those built-in DVD player decoders will only function if your receiver has 6-channel inputs. Not many do these days. You'll also find the quality is better and processing options greater if you use the decoders on a receiver.