Welcome to the forum.
I cannot think of a way to do this from PrPro, but Adobe Audition can handle 16 discrete Audio Channels. Some formats, like WMA (probably several others too) can handle multiple separate Audio Channels, but at that point, you would have two separate files. Now, I am not sure of a muxing utility, that can wrap the separate files into one MOV, but there are bound to be some available.
There was also a similar post in this forum, not that long ago. I do not recall the responses, or if resolution was reached.
Hope that others have an easy solution for you.
[Edit] I believe that this is the THREAD, that I was thinking of, but do not know how much use it will be to you.
Any clues as to if this is even possible?
From Premiere Pro, it is not. Your only options are to mix down to 5.1, stereo or mono. Or, as Bill suggested, remix in a proper audio suite.
Thanks for your help. Not the answer i wanted but thanks!
Am i correct in believing that the 16ch master is there to output to devices capable of outputting 16 discrete channels?
If i install a BMD SDI Card that will support 16 embedded channels will this feed to this card happily as 16 channels?
I could obviously then feed to the recorder as SDI and capture in real time. Far from ideal but a solution i guess...