A home made module. It is a pair of VCA working  as a CV crossfader/mixer between direct signal (A9) and an audio effect chain -the loop- connected between "Send" & "Return" Jacks on the front panel. The output of the mix between loop and direct sound goes directly to the Matrix ( pin13). The mix level is controled by CV coming from matrix output B9.

 

Schematic of the FX Loop (gif)