I built the DemoRunner (tip of develop) on MacOS 11.6.8.
If I run the Audio Recording demo and go to the audio settings and disable Input 1+2, I get a very loud noise! This is when using the built-in output and built-in mic. (Watch out - it is indeed very loud…)
It is the same when using another input (in this case Soundflower).
Also, there’s no sound coming from the input.
My desktop app using Tracktion is showing the same behaviour on both Mac and Windows.