As far as I know:
(A) the MB2P doesn't have inserts. You'd have to pull the line level signal out of an output and route it to the AVII's input, run the stereo out of the AVII back to a pair of line-level inputs where you could take the sum (an exceptionally bad idea, IMO) or the wet-only** signal (a much better idea) into the MB2P.
** (B) The AVII sucks and I wouldn't recommend this at all in the first place.
You can route whatever you want to whatever verb you want and listen to it. But committing a wet signal to tape (or digits) is a wonderful way to paint yourself into a corner (a bad-sounding, noisy corner in relation to the AVII) for absolutely no reason at all.
If you want a real-time "preview" type signal, you can always use an aux (as intended in the first place) to do this with the AVII and then use decent sounding, non-noisy-as-hell effects in the box - in the context of the mix (which is always the best time to make such decisions).
