Anyway - there are a couple of odd limitations that I wanted to check
1) Our Sony RDR-HX950 DVD/HDD has HDMI and Coax out - in the manual for the Sony it says to choose either HDMI OR Coax - the Denon will accept only Video over HDMI and needs optical or Coax for the digital audio.
Hooking up both the HDMI and the Coax DOES work though - does this make sense or could it be a lesser form of Coax digital output (we're using a standard RCA cable - should I get proper coax?)
2) Also we have a Zinwell Freeview HD box - this also has HDMI, Coax and Optical out. Hooking up the Coax to the second coax port on the Denon produces no sound. Hooking up the standard Audio L/R out to the Denon does produce sound. Is this because the Freeview HD signal is not carrying any Digital audio to output over Coax?