I would go to a Denon owners thread as they are not the easiest receivers to understand on setup and capabilities.
I just bought a Denon AVR-790 receiver because it allows all your inputs to be sent via a single HDMI cable to your TV (video and audio).
My prior setup was a HDMI cable from the cable box to TV. So now I ran an HDMI from the cable box to the receiver and then an HDMI cable from the Denon receiver to the Samsung TV. I get picture but no audio from the TV speakers. I consulted the Denon manual and it says to make sure the HDMI Audio Out is set from "AMP" to "TV", which I already did.
Oddly, if I turn on or off the Denon receiver, there's a slight interuption in picture and I get sound briefly (1-1.5 sec) but the picture refreshed quickly again and I just get picture only again.