When you build the kit, there will be an extra green/blue set of wires in the CAT5 for the input wiring. On the selector switch end, those would wire to the center switches to capture the tape output, then on the other end of the preamp you would move the green/blue CAT5 connections already there to the jacks closest to the power entry module, then wire in your new green/blue wires to the now empty pair of jacks.