Hi Horpsnark,
I'm not familiar with all of these modules, but it seems to me there are no envelopes or (dedicated) LFO or VCAs or mixers in this system. In this case the Pico VCO will just sound like a continuous drone. There will also be no automated/continuous modulation in your filters or any other modules. Everything will be quite static.
How will you sequence notes or triggers? Do you have some external sequencer? I guess Marbles will sequence, but not in a really controlled way.
How will you output all of these instruments to make sound? Do you have an external mixer?
You have three instances of Drum2 in your system. Unless you really really like the Drum2, it's probably more fun and more creatively challenging to have different modules.
I like the Black Dual VCF personally, but it's quite huge. In such a small system as yours, I would probably pick another filter so you can use that space for other modules.
If I was making this, my first step from this point would be to have some external sequencer. I like the Beatstep Pro, it has two lanes of melody, velocity (can be used for other modulation) and gates. There's also 8 individual drum gates. You may need to get some extra cables to deal with the high voltage coming from the Beatstep gates. Then I would add something like NANO Quart or Intellijel Quadra or Mutable Instruments Stages (clone) to have some envelopes to work with. Envelopes can also be LFOs when put to loop.
Good luck!
