AIR not yet compatible with Yosemite for MAC

[Jean-Marie]

I do wonder what they're changing in the OS that can affect an app like Devialet AIR so fundamentally though.

I expect that AIR has to present itself to the kernel as an audio device driver - so it's rather more than an application program, and therefore might be expected to have to change from one release of the OS to the next. Only speculation on my part, though.

I suspect it is the case since it appears on the system preference as an Sound card. So I suspect that there are two parts:
1st part is a virtual sound card with an audio driver as you mention and as being something running in the kernel is heavily susceptible to any OS architectural change
2nd part is the application making the bridge between the virtual sound card and the network to send the audio to the Devialet over IP.

/Jean-Marie