Volumio 2 and HifiBerry Digi+, Basic setup

Hello all,

I am new to all this so need a bit of a help if possible.

I have:
RaspberryPi B+
HifiBerry Digi+, attached with green LED on
Volumio 2, fresh install
Meridian DSP5000 (about 20 years old?)

I have a fresh install of Volumio 2 up and running and can play Spotify / Web Radios through the audio jack on the Raspberry Pi.

I would like to use the digital coax out on the HifiBerry Digi+ to play Spotify / Web Radios etc. through the Meridian DSP5000 but it just doesn’t work.

I have turned on I2S DAC, selected ‘Hifiberry DIGI’, restarted and the Output Device is set to ‘Hifiberry DAC’. Playing a webradio I can still hear it through the audio jack connection. If I lift up the flap on the Optical Out on the Digi+ there is no light.

Can anyone tell me how to go about getting this to work? I’m afraid I don’t really know where to start.

Many thanks,