I'm pretty sure that thing doesn't have individual track outs (it's already sporting 8 inputs and all the usual output stuff for an all-in-one, and it isn't physically that big of a box so I'm just assuming), but, just as an idea, can you USB to a computer and put all 16 of your tracks into a DAW, then have a control surface type mixer control the tracks in the DAW?
I'm not a computer guy I just use all-in-one's, tape, and outboard stuff, but my guess is that a control surface kind of board running the mix on some software mixer might be the route, since small all-in-one machines aren't usually capable of individual track outs. As an input mixer though you just take all your extra mics/lines (whatever) and stick them into a submix on your mixer, and from that into your recorder panned L/R hard (although I hope that wasn't what you were asking but you never can be sure).
