I’ve started some implementation on the DaisySeed: Polyphonic synthesizer, first steps with DaisySeed (DIY MIDI module based on STM32, no arduino yet) - YouTube
It is a combination of the existing modules combined with a little engine to handle the polyphonic voice assignment. Unfortunately I cannot port it into an arduino project because it seems since the last update the audio in/out is broken.
Audio does not work with latest arduino board/lib/code
When I can get the audio back to work I would like to make a little project open on GitHub.