surroundophile's last post adds fuel to my theory.

he doesn't see the phase shift between analog and digital because his speakers are equidistant from the listening position.

this means that there is no time-arrival difference between the 2 modes of redirected bass to the sub.

the digital delay settings use the front speakers as a zero point, regardless of what distance you select. from that reference point, the delay is added to the difference of the closer speakers.

surroundophile (and anyone who has all sats placed equidistant) actually has no digital delay applied to his system, therefore, no difference when switching to 6 ch bypass.

as far as the ICBM using a 2nd order low pass, i don't understand the logic of that at all. that slope would not match anything in BM mode. OTOH, if using vented mains, the 6th order LP is correct.

if you have, say, vented mains, and you selected the 2nd order LP, you would have a 12DB/octave slope on your sub and a 36DB/octave slope on your mains (vented roll-off of 24DB/oct + 12DB/oct HP applied = 36DB/oct). this, plus the unknown Q of the HP filter and how it reacts to the vented mains, would likely cause a hump at crossover, which would have nothing to do with phase.

also note, the ICBM manual claims less than 1 degree phase shift at crossover.

someone needs to design a delay system that sets the SUB as the zero point and is analog, after D/A, and thus a set-it-and-leave-it system (or...maybe someone already has )