i have run my mp-2 into an oade digi mid ua-5 a few times. get yourself a good pair of xlr>rca cables. maybe someone on this board can make them for you. connect xlr out of the mp-2 into the rca ins of the ua-5.
you can also use a stereo 1/8" miniplug>stereo rca cable
i find the ua-5 to be a fine a/d converter, but i dont like the access to the gain knob for the rca inputs which is a tiny knob in the rear of the ua-5. a 1-1/2" 10-32 wellnut that can be had at a good hardware store and can make the gain knob a little easier to use
do not run mp-2 XLR out > ua-5 XLR (or TRS) in, you will be going from mp-2 preamp to ua-5 preamp.
i run my mp-2 gain all the way down, that is the gain knobs totally counterclockwise, and when music starts playing adjust only the side that is a little lower levelwise than the other to even out. then adjust the rca gain on the rear of the ua-5 so the high points are blinking the over led which goes off i believe at -3db.
hope this helps...have fun