There's a lot of fun to be had indeed
If what you want is specifically (and only) panning and volume, then the volume can already be taken care of using the VCA mod matrix column. Controlling panning would require something like a
Doepfer A-134 panning module. So perhaps it's time to start a eurorack modular to expand your MxB?
In addition to simply panning the MxB mono output (left channel), you could also connect the stereo outputs to the A-134 to vary the left/right levels while using the MxB's on board FX. Another option is to use the insert jack on the MxB to tap a pre-FX mono signal (i.e. using the insert as a direct out, like
this) that you could run through the panning module (and other processing) while still using the stereo outputs with the onboard FX - you'd then have two outputs from the MxB which could be processed separately. There are also eurorack CV-controllable effect modules of all kinds that you could use to extend this further.
(You could conceivably also use a CV-to-MIDI box to convert the MxB CV outputs into MIDI CC messages that in turn could control FX/processing units with MIDI inputs, but that's much less clear cut and you'd lose control resolution and fine timing. However, IMO, the eurorack module(s) solution would be more 'natural', easy and fun.)
