Quote Originally Posted by Woochifer
I never bought into DPLII for one simple reason: there are no sources out there that are encoded specifically for DPLII. This means that DPLII is no different than any other DSP mode. It might sound better than the others, but it's still another layer of processing on top of a specific decoding scheme that makes the quality of the playback a lot more random.

DPL is different in that it decodes two-channel Dolby Surround soundtracks that were specifically mixed with DPL decoding in mind. The DPL scheme entails an encoded monophonic bandwidth-restricted surround track folded into the two-channel mix, along with extracted center channel info. That's really all that gets encoded into a Dolby Surround soundtrack.

Whatever DPLII adds with the channel steering and redirecting main channel info into the surrounds is conceptually the same as what one of those room simulating DSP modes does. In my listenings, DPLII can definitely add to the immersive effect, but depending on how the Dolby Surround soundtrack was mixed, it can also create some very bizarre sounding effects as well.

In general, I prefer to stick with straight DPL for TV viewing, yet even there the quality of the surround effect and center channel redirecting will vary. But, at least it won't steer dialog or other sounds clearly intended for the front channels into the surrounds.

Five-channel stereo is too gimmicky for my long-term listening enjoyment. Dolby Surround soundtracks with a lot of ambient cues have out-of-phase signals folded into the mix, and in five-channel stereo mode, those just sound horrible. And having voices all around with no imaging coherency or directionality defeats the whole purpose of surround sound. Might as well just plug in a pair of Bose 901s if you want that same "mono everywhere" effect. Some music sounds decent in five-channel stereo, but as with DPLII, the playback quality varies too much for me to keep it on for very long.
Yes, I've heard bizarre sound effects from Dolby tracks using PLII, mostly with DVD extras (voices coming from rear speakers, nothing from the center). But what is different, correct me if I'm wrong, is that with PLII, the rearr matrix is not mono, that is you can and will get different sounds from the left and right rears where in original PL you get a mono sound split to the two speakers. Again, for watching, tv, I really enjoy it. It's also of course necessary for gaming, my PS2, for instance. And those are really the only two sources I'll use PLII for.