Thank you for the extremely thoughtful response to my question about modular synthesis. It'll be a while until I'm able to play with one again, but in the meantime I'd like to learn more using a software equivalent. I currently use Ableton with some free soft synth plugins (Synth1 and P8), but I'd like to use something that better replicates the workflow of routing one unit to another (not necessarily by connecting virtual patch cables ala Reason, just sending information). Any suggestions?

You’re welcome!

All of these look good, and they’re free! http://www.vst4free.com/index.php?plug-ins=Modular

KarmaFX also has one which looks pretty good, though it’s a little over $100.

I WOULD get one which physically emulates a real modular as accurately as possible. Obviously, soundwise it makes no difference, but being able to clearly see the connection is helpful for visualization and for quickly seeing how everything is set up, and will really teach you modular synthesis, as most synths offer some subtle rerouting capabilities anyway.

A cool hardware midway point would be to get the Korg MS20 mini. Thom and Nigel use an MS20, and it’s a very cool synth. You could also look for a software emulator of that.

I’m not terribly versed in VST’s, to be honest, so you should definitely supplement this with your own searching.