MacBook Pro 2016 sound output stuck on Airplay
I used my MPB (2016) with my Apple TV a day or two ago. Today I discovered I could get no sound from my desktop sound system. System Preferences —> shows my sound output set to Apple TV (AirPlay), and offers no other choices. (See screen shot.) I've punched the volume controls, mute/unmute ... nothing seems to work. I restarted the machine, but no joy. Suggestions?
I run High Sierra (10.13.1)
MacBook Pro (13-inch, Late 2016, 4 TBT3), macOS High Sierra (10.13.1)