If you need to connect the IR output of a Centro unit to a Muxlab matrix for transmission of the IR through the HDMI balun system, you cannot use the stereo-stereo cables which are supplied with the Centro.
Both the Centro IR outputs, and the Muxlab IR inputs have stereo sockets with 3 pins:
TIP: Pin1
RING: Pin2
SLEEVE: Pin3
At the Centro end, the pins required are the tip & the ring pins 1 & 2.
At the Muxlab IR RX end, the pins required are the tip and the ring pins 1 & 2.
Connect the Centro Pin1 to Muxlab Pin1, and connect Centro Pin2 to Muxlab Pin2. Connect nothing to Pin3 of the Muxlab plug. Do not use mono jack-jack leads.