You have SBD > DR07. His terminology of "matrix mix" and most taper's terminology of "matrix mix" is different.
Most tapers think of a "matrix" as being a SBD + AUD mix, frequently recorded onto separate tracks and then mixed at home, although sometimes it means an "on the fly matrix" of room mics + sbd feed into a 2 track recorder.
Most mixing guys think of a matrix as being the house mix to feed the PA, whatever it is to make the room sound good, and it's almost never mixed to be optimal for recording purposes. Tapers on the other hand call this a "board feed".
Taper's slang of matrix has always confused me. To me a matrix involves rows and columns of numbers, and I never could figure out why that has become common slang around here. I generally title my 4 channel seeds as "banddate.akg414-sbd-mix.flac16f" rather than "banddate.matrix.flac16f" avoid confusion.