Ex Soundflower users may have a new solution for audio routing on Mac, thanks to a free solution posted recently to GitHub by Existential Audio.
Running in the background as a virtual input/output, and appearing in your DAW alongside your in/out interface options, Blackhole can shuttle audio around your system to connect anything to anything under the hood.
You could, for example, run one DAW's output into another DAW, record the audio output of your browser in another piece of software, or use Blackhole to divert your Mac's alerts and sound effects elsewhere for processing.
What happened to Soundflower?
First released in 2004, the solution to routing audio from place to place using a virtual driver was quick, elegant, and worked directly with the Mac audio architecture.
Time was, you could set your Mac's main audio output to Soundflower, then choose Soundflower as an input in your DAW, and hey presto – you got to record anything from your system within your DAW.
But then, as the Mac audio archtecture started to change, Soundflower was left unchanged, and eventually began to fail when installed on OS X versions 10.10 and above. Users of newer macOS versions will find Blackhole a simple replacement, although those who've upgraded to Catalina can't be guaranteed an easy ride.
You can download the latest release of Blackhole from Existential Audio's Releases page on GitHub.