Hi Ridvan,
Thanks for writing about this. This is a known bug on Mac, that we are currently working on fixing.
Animation Paper IS recognizing your headphones, but ONLY when it is launched. – And then it will work for the whole session.
If you first run AP and then connect your headphones, then AP is not recognizing the correct audio output (your headphones).
This will be fixed for the next release, but for now, just restart AP 🙂
Please let me know if you are still having problems!
Niels