Matrix Ctrlr extension :

The extension is an optional PCB that copies Midi and Power Supply connectors of the Matrix Ctrlr mainboard on a DIL-20 header connector.

The idea is to use the Matrix Ctrlr extension in your rack to connect all the midi and power supply cables to your synths and use a 20 wires ribbon flat cable or a DB25 cable to connect to the Matrix Ctrlr device via the extension port on the main board. This way, the Matrix Ctrlr lays on your desktop without a lot of cables, but just one !

Matrix Ctrlr Extension schematic 1.1 (blue edition) :

Matrix_Ctrlr_extension_sch_v1.1