Bob, you didn't describe what your understanding was, but crossovers don't suddenly cut off the sound above or below the selected frequency. The typical crossovers in HT receivers roll off(not cut off)the frequency response to the speakers at 12dB per octave below the selected frequency and to the sub at 24db per octave above that frequency. For example, S&V includes a test of the crossover in their bass-management results for receivers, and you'll note here that in their excellent results for the
Onkyo 706 that the roll-offs met the 12dB and 24dB standard at the 80Hz test frequency.
