The UI is rather minimalist and not intuitive. For example. Audirvana Studio when taking over the sound output of the Mac does not have an easy/intuitive way to switch it off. I need to quit and with the help menu being less than helpful is a source of frustration. The UI needs a big fix in a big hurry. I am not shocked by the subscription model and with a Roon lifetime subscription Audirvana will need to make big strides. At $50 I may stay, at $70 it is a bigger stretch at this point. Hoping for big changes in the near future.
There is a tiny padlock icon in the bottom right part of the screen to stop playback and unlock the audio device.
There were few post complaining about this being not obvious.