AFAIK the woofer has always been directly driven on M3/M40... and at first glance that still may be true. The crossover on the right (assuming that's from your M3 ?) only seems to have one additional capacitor, so it's likely that the woofer is still directly driven. Might be worth tracing out the circuit, probably just a one layer PCB...
You're right, the M3's woofer is direct. In fact the crossover component values are identical except for the addition of what appears to be a 2.7ohm resistor. I'm going to have to try shorting that extra resistor out afterwords - the weaker tweeter output may be why I feel the M3s are dull sounding compared to my other Axioms.
