Hey guys. This is a silly question but what is the actual difference between DTS and PLIIx?

DTS is a data-compression technology (like MP3 or Dolby Digital).

PLIIx is surround processing technology.

Ok. Thanks for answering here too . I was watching Assault on Precinct 13 which is supposed to have DTS but for some reason when I hit the DTS button on my Sherwood I get silence. I believe the Sherwood has a similar menu to the 990. Does anyone know what I need to do to hear the DTS tracks?

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.

You have to select the DTS track on the DVD player.

Hey it worked. What a dweeby newby question. :p I have just always watched it in Dolby and never explored DTS. Okay so here I am watching Assault on Precinct 13 and I switched it over midway through to DTS. First thing I notice is its louder. I have it with the PLIIX. It sounds great. Why don't they all have DTS?

DTS is typically about 4dB louder than Dolby Digital, which is sometimes suggested as a reason that many people prefer DTS - the ears can equate "louder" sound to "better" sound.

The reason that many discs do not include DTS is "bit budget". A DVD has a finite amount of space, and DTS typically takes more space than Dolby Digital. At one time, studios would get around this by releasing separate Dolby Digital 5.1 and DTS 5.1 discs (with a legacy DD 2.0 track on the DTS disc to satisfy the DVD standard). That practice has largely ceased, and instead we see DTS 5.1 tracks coexisting on discs with DD 5.1 tracks. The combination of those two cuts into the space left for video (potentially requiring higher compression, which incurs a possible decrease in image quality) and extra features.

Besides being louder, are there any other real differences in sound quality? I have not been watching long enough here to really come to a conclusion but my instincts are that it is smoother? That could just be the 4dbs talking though.

Cliff, what do you have your sub set to in relation to your Dolby for DTS? I notice the sub output is a lot less. Thanks.

Do you mean the LFE level trim settings or the sub channel trim?

For sub channel trim I have the preamp set to 0dB and used the sub amp volume control to balance the subwoofer with the main speakers.

After setting the volume on the subwoofer I set the LFE level trim to -4dB for Dolby Digital and +10dB for DTS.