I have iMac late 2013, El Capitan 10.11.6 installed.
Audio device is JBL Authentics L8.
The audio device only appears in iTunes airplay list and in Preferences->Sound, but in sound preferences it is marked as "selected device does not provide an audio output control" (it is translation, i use non-english mac os version).
At the top mac os panel in AirPlay menu i can't see my audio device. So as in youtube.