The 1/4" output is a balanced Tip Ring Sleeve and is designed to drive the MBP. Use a cable with 1/4" TRS on one end and a n XLR on the other.
RAG
Thanks for the reply. and to the two previous posters for the proper cables.
Makes me closer to getting one of these as it'd take care of most if not all of my needs.
For the people who already have one. Is the tuner fast and accurate enough to use for setting intonation? I currently use a Boss TU-3 for that but if the Plex took care of that too I'd give the Boss to a nephew.