MOTM

a) I have never seen a +-15V regulated wall wart. I have seen +-12V (they 
use a 5-pin DIN, a la MIDI). But this will not work with MOTM.

b) your best bet is to get a 5U tall case, put a MOTM-900 in there, and 
leave it. Then, when needed, remove modules from
the studio and place in there.

Paul S.