But this isn't how it happens. Like I mentioned, most pre/pros and receivers when they do digital BM use a 24dB/octave low pass, and a 12 dB/octave high pass. Because the slopes are different, the phase delays are different. That difference is 90 deg per 6 db/octave of slope. So ... for the low pass, the shift is 360 deg, and for the high pass, it's 180 deg. Hence the ubiquitous 180 deg phase switch on subs. But that isn't all there is. Unless your sub is right on top of a main speaker, there will be additional phase delay introduced by the actual difference in that distance. Plus, even though digital crossovers are designed to have the same phase characteristics of analog crossovers, there *is* an extra delay due to the digital processing itself. Hence the fact that it is really difficult to get all the phase relations to match up between using digital crossovers in a pre/pro, analog crossovers in a pre/pro (if present), or whatever you're doing with BM in the player (if anything).

This is why Soundhound is right on the money when he says he uses identical 24dB/octave slopes for HP and LP filters for all sources.

But... There is a small problem with the identical 24dB/octave approach. Real example. 80 Hz crossover (with low pass and high pass filters). 24dB/octave LP means 24dB/80 Hz for the LP slope. But the high pass slope is also 24dB/octave which is 24dB/40 Hz. They are not equal. Hence I don't see how you get flat freq response through the crossover.

The funny thing, is that after the 950 I went with a Lexicon pre/pro, which actually uses identical 24 dB/octave slopes. So there's something there, but no one has yet explained exactly how it works.