Your signature line lists the Edirol R-09. If you still have that, I would run the MiniMP > line in on the R-09.
I owned an MiniMP for about a year and ran it into my Edirol R-1 with great results. The R-09 is a step up so i would imagine improved results. You will need a stereo XLR to 1/8" cable to do this.
This of course assumes that you wanted to strictly do 2 channel vs 4 channel in R-4.
Those are my thoughts. The MiniMP is a fanastic pre. I am very pleased with my Busman T-Mod FR2LE, but I did like the sound of my MiniMP better.