Post

Cascaded quad VCA is a very good option, both for audio and modulation.
For example Intellijel
https://www.modulargrid.net/e/intellijel-quad-vca
Or some clone of Veils.
An auxiliary mixer for modulation will give you plenty of play if you eventually want to add effects modules with feedback.
I have this in my sights
https://www.modulargrid.net/e/st-modular-matrico
and a classic
https://www.modulargrid.net/e/doepfer-a-138m
The filter theme depends a lot on your tastes...
Greetings,