The XLR outs ARE fully balanced. The unit does use four DACs per channel for Stereo playback, but the output from the four DACs is still differential - i.e. the output is +/-L and +/-R. We use four channels of our mod board to allow for both +L, -L, +R and -R. The remainder fo the channels, if uses, are for FL, FR, C, SL, SR.
The RCA's are wired from the XLR +, so that both XLR's as fully balanced outputs are available as well as in-phase RCA's.
Thanks and please don't hesitate to call with any questions.