Got a shiny new microcontroller, SBC, or other device? Already ported DOOM and an NES emulator to it? Great, time to make a MIDI synth out of it.
Now, you COULD go down the rabbit hole of Digital Synthesis... while I won't discourage you, for those of us who HAVE built a simple synth before, digging out assembly manuals to reimplement the wheel is not a good use of time.
What if there was a portable core for making synthesizers? What if it had the following features:
* High performance, suitable for real-time usage
* High-quality sound output
* Scalable to a range of devices, from microcontrollers on up to Unix-based SBCs, or embedded into a VST or other lib
* Modular: add MIDI, XSC, digital output, additive or sample-based generators, etc. to suit your needs
* Extensible, with easily understood "hooks" to interface with your target hardware. Got a toy keyboard? You write the key demux, SynthGuts does the rest.