Roger Dressler of Dolby recently wrote about low pass filters and phase shift in http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=332595&perpage=20&pagenumber=4 with regard to Center, Left and Right speakers, specifically:
Quote:

in a configuration where the C is set "small" and L/R are "large" with no subwoofer, the C bass will be extracted with a lowpass filter and summed with L/R. If the bass in L/R and C is common, then the sum will depend on the phase relationships of the LPF. Turns out that typical DSPs use 4th order LPF. This is fine for driving a sub, but when used in bass redirection as above, the phase shift causes substantial bass cancellation, thus sounding weaker than the 2-ch source played in stereo. We have been instructing the chip makers to switch to 2nd order filter for these specific redirection modes, and this solves the problem.

This is not isolated to PLII, but affects any decoder mode.

I don't know if the 950 uses 2nd or 4th order filters to redirect, but apparently, in some LFE cases, it matters.

Best,

Will