ive never done the 4 mic mix, but i did a 3 mic mix several times
i ran a nak cm300 (internally battery powered) > xlr > line transformer, also xlr > 1/4" > 1/4' to rca > rca splitter to dual mono in the rca's
i basically just ran the nak input all the way up, and adjusted the phantom to my gefell m300s to get desired levels