How did you implement the side-chain compression? (I think I am hearing that.) We can also move offline of HN if you would rather discuss there. gene at semitone dot audio.

Happy to do both!

But answering here if I understand correctly: I use (at the moment) a mostly serial chain architecture.

I think what you're asking is whether I'm using signals from one instrument (or other component) to drive another. Not as much as a first class feature similar to what you'd find in Ableton.

So, for example, I don't have today something that will drive low-pass cutoff frequency on a synth based on the kick drum sine wave decay.

Same idea you're mentioning?

On my list to get to but not there yet! I tend to add things as they come up in the process of making music, rather than approach this as a software-first-music-second project.