FWIW, I was unable to get Blackhole working reliably (having dealt with this problem several times on Windows, Linux and Mac in the past). It seems very sensitive to which devices are being used in aggregate audio outputs. Might be MacOS's fault, but in any case it didn't work very well when I tried it.

> Blackhole[1] is a better

I took a quick look at the issues list & features request, and I'm going to disagree with you there. For example, you can't route the output to different monitor devices and change their volumes. (I often use my headphones as a mixing monitor.) It looks like a neat free alternative, though.