No sound from optical or coax digital inputs

Back ground:
Had system for many years with no problem. Just got a Topfield PVR and decided to use the coax digital input for the audio (as it was not being used). Connected it up and assigned coax to spare channel on denon 1602. No Sound.

Fault finding:

• Checked that coax output on Topfield was working - it was.
• Tried a different spare channel on Receiver - no sound.
• Tried an already used channel (DVD) with coax input - no sound.
• Changed DVD input back to optical and now it will not work.
• Reset the microprocessor as detailed in manual - this is where it gets interesting. The default setting both the optical and coax worked with the default setting (ie optical assigned to the TV input and the coax assigned to the DVD input). However the sound out was only Dolby Pro-logic, not DTS or Dolby digital.