https://github.com/jstilwell/MacAudioInputLocker

I maintain a fork of this app, which allows you to quickly set and lock your audio input device, so that they don't switch your audio input device to bluetooth as soon as you turn them on. Mostly because of the first gen of these headphones. They LOVED to keep the mic on at all times with no way to disable that behavior.

I assume it's the same with the second gen.