[This post was written using Rack v0.6. The following will continue to work until Rack v2, however this information is now largely obsolete given that VCV Bridge is deprecated and unsupported as of Rack v1]
I recently started using VCV Rack. Rack is a cross-platform open-source modular synthesizer that aims to model Eurorack standards in software. While it is yet to hit version 1.0, Rack already has a sizeable number of free (and paid) plugins that extend functionality of the software, and an active community. Rack runs as a standalone application, but also plays nicely with other DAWs.
The Rack manual outlines how to use it with several audio applications, but details for integrating it with some of the software I often return to—Max and Cubase—was missing from the Bridge page at the time of this writing. It seems that some updates to the manual (detailing how to use Rack with Cubase) are waiting for review in GitHub, but the steps listed don’t appear to work with Cubase on macOS.
In the meantime, though here are the steps I have used to get audio from Rack in and out of Cubase. A post about using Rack with Max will follow. [See above]