My setup is the Apple TV 4 and Denon receiver connected to two hdmi ports on a Samsung smart tv (all controlled by CEC). Regardless of content all I see on my receiver's display is stereo sound but others on this site have mentioned 5.1 sound. Does ARC via hdmi only support stereo? Do I need to dig out an optical cable from my garage? Sound isn't my forte (and I hate the unnecessary complexity of receivers) so I'm not sure what I'm doing wrong.