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Following on from Louigi's question, I want to say on this mailing list a couple of things about VCV Rack that i've said often on IRC but not elsewhere. Really just two.
1) I want to give HUGE thanks and congratulations for Andrew Belt and what he has done with VCV Rack. Not so much the program itself, but the ecosystem he either deliberately or accidentally created around it. Some of you (*cough* Dave *cough*) might remember that before I wrote Ardour and JACK, my first foray into Linux audio was something called Quasimodo. Powered by a reimplementation of CSound, the GUI was a lot like VCV Rack (and other similar software). Quasimodo never succeeded, for a variety of reasons, and it is so good to see a GPL'ed modular synth now finally really finding and creating a community and success. The visual appeal, ease of use, and relatively simple module API of VCV Rack have all been critical in its success, and Andrew deserves many kudos for this. It really is amazing to see the set of available modules (and their quality) and the dual business model (no-cost vs. paid) for modules. I'm actually jealous.
2) All that being said, as a programmer, the internals of VCV Rack's engine are deeply disturbing. It is really amazing that VCV Rack works as well as it does. It isn't properly coupled to the audio hardware at all (it uses a timer to drive the graph), and it can't be trivially modified. Thankfully, someone has done the modification for the VST version of VCVRack (because in a plugin, you have no choice), and so perhaps the redesign might make it back into the mainline code. Given the lovely to use GUI and the fantastic ecosystem, it's a little sad to see the internal code suggest almost no understanding of how to write a realtime audio application. Maybe Andrew had his reasons for the internal design - I don't know. But it certainly makes it much more likely to have audio glitches and to be incapable of operating at the lowest latencies. It works well enough for me, however (and is a huge risk because I could spend hours playing with it).