Now we might get somewhere...
It sounds like you haven't assigned the optical input on the Denon. You need to go in set-up and "attach" the optical to Cable/Sat.
Makes no difference(been ages since I looked at the rear panel of that AVR to see its labeling, but however it is marked is irrelevant anyway) if the optical says cable/sat or not. You still have to assign it.
And yes, that MP cable is the correct one. (toslink stands for Toshiba Link. It is their take on the SPDIF protocol. The "other" being digital coax)Go to the full post