I started to wonder what the Sub37 would look like if it was built all out of Eurorack... so I planned it out as a thought experiment.
Wow I think it would be quite a beast, and it makes me appreciate just how much you get in the box!

https://cdn.modulargrid.net/img/racks/modulargrid_690139.jpg
ModularGrid Rack

--and back to the topic of the actual thread..
I found shooting different envelopes from my DFAM/modular into the Sub37 Filter input sounds awesome BTW.. Also, sending pitch CV from a quantizer lets the Sub37 change keys along with the modular, so that works if you can solo in C on keys. While it might not integrate fully with a modular, with some creative patching it can really sound integrated.

Hope that helps!