Let us know how it works for you - I don't think it's an approach that has been widely used, but it could work well for folks if the right crossover point is used. For the M60, I'd probably try both 40Hz and 60Hz (the -3dB point is 37Hz, so they'll definitely be rolling off naturally with a 40Hz crossover such that there wouldn't be much of a double bass issue, but the 60Hz would provide a little bass reinforcement that could work well too).