I have a Denon AVR-S540BT and am unable to get sound through it when watching cable TV. The TV is a Samsung 46D550.
I don't have the cable TV running through the AVR.
* TV optical out to AVR optical 1/TV Audio
* AVR HDMI out/Monitor/ARC to TV HDMI In 2
Both connections are just like this:
Which says I should be getting audio.
* coax cable in to cable box
* cable box HDMI to TV HDMI In 1
* Blu-Ray HDMI to AVR HDMI DVD/Blu-Ray In
I think I've tried every combo of settings in the Video menu.
I also had a Yamaha HTR-4065BL connected this way and was able to get audio through the AVR when watching TV.
But the optical-in on it was one of the numbered AV inputs (AV4), and the remote had buttons for HDMI 1-4 and AV 1-7.
On the Denon, the optical in is just part of a separate digital audio in section.