Ken you are correct, the M3's do not have a physical crossover, they just let the 6.5" roll off and a diode or was it a resistor hooked up to the tweeter. I would imagine the M3s are the least changed out of all the Axiom lineup.

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