Coaxial output not working on Marantz CD4000

I have a Njoe Tjoeb modded Marantz cd4000, Always used either through headphone output or RCA out to amplifier.
Just bought a Hifiman ef499 and wanting to use digital output via coaxial cable.
I have plugged cable in both ends, selected Coax on the ef499, but no sound.
Checked ef499 with digital input from phone and PC and they work fine.
Is there a switch I need to set on the cd4000 to activate digital output?
 
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