Does ARC only relay the sound of a TVs built in tuner and apps back to the AV receiver or can it also relay the sound of other inputs. I have the ARC input (HDMI1) of my TV connected to the ARC output of my AV receiver. If I use a source on the TVs HDMI2 input, can the sound be sent back to my receiver through ARC? All my receivers HDMI inputs are used so I have a couple of sources going directly into my TV. I'd like to be able to listen to them through the receiver, not just the TV speakers. I've tried the optical output of the TV to the receiver and I keep getting an echo (but I do get sound). With ARC, I get no sound (I did disconnect the optical cable for testing ARC). I've never used ARC before on any system so I don't even know if it only works on built in tuner/apps or any input.