80hz and lower is pretty much nondirectional and this is where that punch lies, 50-70hz. This is where the MBM is supposed to work well and enhance that usual crossover point which could have a slight dip between the roll off of the mains to the sub. I run my M80s at 40hz to avoid this \:\) I also found running the A1400 greatly improved that mid bass punch opposed to my 3808 alone.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70