sfrecord~ is pretty much unusable for multichannel recording in my experience. On mac I record in reaper using a modified version of soundflower that does 32 channels. On windows I think you might be able to use the rearoute asio driver to pipe max’s audio into reaper.
Endless Series v3 out now – A unique synthesis and effect plugin/app based on the Shepard Tone auditory illusion. http://www.olilarkin.co.uk