Originally Posted by JosephD05
I have a 7.1 setup. I meant the source material is 5.1 in it's native mode. I have an Onkyo 805, not sure what's better. Sometimes the rears light up more than others.
Originally Posted by BIslander
Back to your original question - there's no sound degradation using a DSP like THX Ultra 2, PLIIx, or Logic 7. But, the audio does get changed, of course, to reroute some of the surround audio to your rear speakers. I don't have a 7.1 system myself, but from what I've read, 7.1 matrixing is pretty much a hit with those who do.
If you are talking about the THX Ultra 2 surround mode to create 7.1 channels from a 5.1 source (and not just Re-EQ, decorrelation, etc.), keep in mind that the Ultra 2 surround mode creates only a decorrelated mono channel in the back surrounds. THX recommends that the back surrounds be close together when using this mode.
DPLIIX, on the other hand, will create stereo back surround channels and the speakers should be spaced apart.
I have an Onkyo 706 with THX Select 2 Surround. Same thing as the Ultra 2 Surround. When I compared it to DPLIIX, DPLIIX was the clear winner. Better separation, better ambience, clearer sound.