The chap that suggested you can record from 6 inputs at once on an M Box is clearly not very aware. SPDIF and analogue are either/or; you choose in settings whether you are recording analogue or digital. The insert points are purely analogue and not related to the I/O of the unit - they are post-input and Pre AD stage. Finally, he seems to have developed a unique way of recording by using the 2 inputs to record 2 separate tracks on a stereo track and then split them - when you might as well just record 2 mono tracks. Hmm.
At the end of the day ProTools only sees 2 inputs when you use an M Box. Therefore you can only record 2 inputs at once.
I’d be interested to hear some of this guy’s recordings though ....
Technical Sales, Jigsaw Systems Ltd