The circular musical note button in the centre of the EDGE remote is a Play/Pause and Mute/Unmute button when used with the EDGE NQ.
The function of the button is source dependant. Where possible the source will be paused and for other sources the output will be muted.
When using the Bluetooth, Airplay, Spotify, Cast or Music Library sources the music button will Play/Pause.
If you are using one of the Analogue/Digital inputs, or listening to Internet Radio, the music button will Mute/Unmute.