teod and bb4tb:

See that's just it. I *do* understand why they use 12 db/octave for the LPF and 24 dB/octave for the HPF: because the slopes on either side of the crossover are identical: 24/80 = 12/40 (for example, for an 80 Hz crossover).

These are just words that aren't backed up by how the slopes add together. Others have stated it before too, but the slopes do not add up. Can you add some more info? (I think I saw once "flat amplitude response" maybe vs "flat energy response" or something.) ??

I actually do now also listen to SACD and DVD-A all large, sub on. (My "weakest" speakers still do -3 dB to 45 Hz. Mains are -3 dB to 30 Hz.) Music doesn't have much content below 40 Hz, and I personally feel you lose more with bad BM than by speakers that roll off too soon. But for movies, I do use digital BM and TA.