I'll have a look for STM32 emulators later on tonight, I can imagine it would save a lot of time and wear and tear on the board plugging it in and out all the time.
STM32 seems to be become something of a standard development platform for all sorts of microcontroller applications and it would be worthwhile me getting a dev board and learning the tools to develop my own apps, and/or write custom firmware for Axoloti.
As for hardware, firstly I want to make a 3U eurorack mounting panel with some rotary encoders, a display and a bunch of jack sockets for clock/gate/cv ins and outs to control, and be controlled by other synth modules.
It needs some pre-amps for the audio ins and outs to buffer higher level signals into and out of it. so I wanted to build them, isn't there a second channel on the audio codec chip? Breaking that out with a pre-amp could be very useful.
Once I get it mounted in the panel I'll solder some headers to the board and develop a breakout board to sit on the headers with the buffers, power regulator, pre amps, display driver if needed, encoder driver, etc.