How do I play audio from a Mac to my Kawai piano via Bluetooth Audio?
Pair the piano as a Bluetooth device, then select it as the audio output in macOS Sound settings.
Enable Bluetooth Audio on your piano. On your Mac, go to System Settings > Sound (or the menu bar volume icon) and select your Kawai piano as the audio output device.
Open any audio application — iTunes, Spotify, GarageBand, etc. — and audio will stream wirelessly to your piano's speakers.