Connected on WiFi but no sound

[RAV061]

Hi folks. I'm seeking some guidance on a streaming problem I'm having.

Here's my set up:
Expert 120, with latest firmware installed (10.1.0)
iMac running latest version of Sierra (10.12.4), with music in latest version of iTunes (12.6.1.25)
Running latest version of Devialet Air (3.0.4)
WiFi seemingly configured fine
Dev 120 'sees' the network and iMac 'sees' the Dev
I have selected 'always stream to it automatically'
WiFi signal seems ok, reporting -70 dBm
Target device buffer is set to 1000 ms
Devialet Air setting window on my iMac faithfully reports the current volume level on the Dev 120 so they are definitely connected
Mute is 'off'


BUT - no music is played on the Dev when I select 'Devialet AIR' from my list of options in System Preferences/Sound Output

Am I missing something obvious?