What is HDMI ARC?
An connection comes in handy when your TV is also the audio source. This is the case when you're watching a Netflix series on your smart TV, for example. If your TV is connected to your receiver via an ARC connection, you can play the sound over the connected speakers. This means you won't need a separate optical cable, leaving you with more free inputs. Another advantage is the ability to control the volume of your speakers with your television's remote control.
What do I need?
For a successful connection, the TV, the connected device, and the HDMI cable must also feature the ARC technology. You can easily check whether or not your devices features ARC. If they do, the letters ARC are displayed next to the HDMI inputs. You need to specifically connect the HDMI cable to these inputs. A cable that supports versions 1.4 and up is always equipped with ARC. Was your cable manufactured before 2009? Then you'll probably need to purchase a new one.