For just this problem, [little-scale] has built a MIDI-controllable DAC for generating control voltages. It’s a simple enough build – a Teensy 2 is used to speak USB MIDI to a laptop.

[Joonas] became frustrated with cheap but crappy MIDI to USB converters, and the better commercial ones were beyond his budget. He used a Teensy LC to build one for himself and it did the job ...