As you were talking about HDMI then it means you have a cable box so this can be easily done with this denon , there are a couple ways of doing this as a matter of fact , here is how you can do this ;
First if it is not already done as far as the tv and cable box goes you simply connect your hdmi cable between the two and set your tv to that source and that's it .
Now for the denon ;
You will take the sound out of the cable box , not the tv for this .and it will be the best source in any case if you want surround sound.
All cable boxes have some form of digital audio out , either optical or digital coaxial but most often optical so you will need an optical cable and connect it from the cable box to the denon`s OPTICAL 1 input at the rear and set the denon to TV , that is where the optical 1 input is assigned then at the front of the denon look for the INPUT MODE button that you may have to press to set the input to DIGITAL if you don't already have sound .
If your cable box has digital coaxial out (rca type cable) then use the coaxial 1 and set the denon to CD that is its assignment then same thing with the INPUT MODE button
That is it .
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