If you're considering the Countryman B3s, I would suggest buying an unterminated/rattail pair from a vendor (Full Compass stocks these and has good prices, especially if you call them), and then having one of the microphone or cablemakers on this board (Chris Church, Ted Gakidis, Darktrain, etc) terminate the pair into a connector of your choice. An 1/8-inch stereo plug could easily be connected to most 9v battery boxes (including the Church UglyBB, among others), which would power the mics, and then into the M10. Several options available.