I don’t think audio is the only way. I’ve had OSC running with CV outputs. Nothing fancy, just the rpi pico builtin dac’s - and running at 1000 Hz sample rate.
I wrote a bit about before.
Thinking about purchasing the ES-9 - #10 by Jens.Peter.Nielsen
OSC (OpenSoundControl) modules in v2? - #17 by Jens.Peter.Nielsen
Bring in measurements from a digital multimeter
Still haven’t gotten around to hooking up my STm32H750 Daisy board - it has better converters (16 bit)
I don’t expect to see a cheaper CV I/O interface. It’s a niche market, you have to write embedded software + drivers for win/linux/mac - and it takes some expensive converters to get the required resolution (relatively speaking, the PCM3168A is €5.198 for 1000+ units)
Here’s some images i found of the ES-9
