Troy, with the M80s, I use my PB13 Ultra for music in 2.1. Yes the M80s work incredibly well on their own, especially when given gobs of power from the A1400 \:\) , but for those of us with out one, allowing the sub to do the work below 60 or even 40 hz frees up the M80s and your receiver's amp section to do the best they can with the higher less demanding frequencies. Once the sub is calibrated properly you won't be able to tell that is playing.

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