[cmrdporcupine]

The reality is the oddities of Yamaha's (& Casio's) way of modeling FM (various pre-set "algorithms" with preset routings of phase modulations) are silly once you have a proper modern interface where you can just draw out whatever "routings" you want.

And chained modulations itself is just a poor unintuitive optimization for just running multiple modulations in parallel additively rather than chaining them in sequence. The Yamaha way of doing this is an optimization for old hardware, and is needlessly confusing.

I had fun writing this: https://github.com/rdaum/sidebands_vst but haven't had a time to go back and finish it (or rewrite in Rust)

[boffinAudio]

That's a fun project - got any interest in a port to JUCE?

https://juce.com/