KiCad boards from 2 GitHub repositories tagged “audio-dsp”, the most starred first; open any of them in PCBKit.
mcbronkowitch/fireflow
FireFlow — a modulation-first ambient groovebox: the modulation system is the instrument, not a layer on top of it. Five independent lanes per part driving a synth, granular, wavetable, resonator or bucket-brigade deck.
MahmoudBasio/DSP-Guitar-MultiFX
Open-source modular real-time embedded DSP guitar multi-effects platform based on Teensy 4.1, with custom hardware, C++ firmware, and real-time control.
mcbronkowitch/fireflow
FireFlow — a modulation-first ambient groovebox: the modulation system is the instrument, not a layer on top of it. Five independent lanes per part driving a synth, granular, wavetable, resonator or bucket-brigade deck.