Module is available as a DIY project only.
This Module is currently available.
SERGE - Multi-Channel Stereo Mixer
The Multi-Channel Stereo Mixer (MCSM) Is a much improved Alternative Output VCA/Mixer/Panner featuring true synth VCA's, specifically designed to sound best for making music. It replaces the former CGS101 DCSM offering smoother responses over the full 0-5V range of envelope control. There are no blind spots, the sound is full-throated, not explosive or hard to control, and when the VCA is off, it is completely silent.
The MCSM is used for standard output level control (or enveloping) and for voltage controlled panning. The MCSM has two independent channels for stereo panning. Each channel in the MCSM has two VC inputs, one for amplitude control and one for panning.
Auxiliary inputs are used to feed other signals into the outputs of the module. Signals applied here will not be affected by knobs or control voltages applied to the module. These are mainly useful for linking other mixers (either manual or voltage controlled) to the output bus.
The output is available at a pair of banana jacks (for routing the signals to other modules within the synthesizer), and at mini-Jacks (for connecting to external amplifiers, tape decks, and other equipment).
The CGS506 can be expanded to larger configurations through the addition of the CGS506-Extension, with each extra 'stage' adding 2 further channels to the mix.
https://www.elby-designs.com/webtek/cgs/serge/cgs506/cgs506.htm
These merchants probably sell this module. Huh?