-- HGsynth
Are you using the ES-9 to connect with VCV rack or other software? If so, this thing looks pretty beastly and you can get what's I'd say is missing virtually. However, if not, or just because you have the blank panel spaces, I could suggest the Batumi expander, which gives you access to more LFO shapes, and some other utilities or random voltage generators? Things like mutes or routers might make this more interactive and fun to play, as well.

-- HGsynth

Noted - I actually have Batumi expander in the post [as in shipping]!
ES-9 just for Ableton Live, haven't used with VCV Rack yet. It's probably an overkill but nice to be able to send CVs and record with a bunch of channels (half of which I don't really use).