Audio In Explained
Audio InIf your DVD player or whatever doesn’t handle HDMI, this is where you connect the audio. Just like with the speaker wire, you’ll have two channels, so two connections, and you’ll need to make sure the + (red) and - (black) are plugged into the correct ports.
Usually, you’ll use standard RCA cables for this. Connecting it up should be pretty straightforward, with one caveat. If you have a turntable, you’ll need to plug it into the Phono inputs; reason being, this uses a special phono cable, and is designed to handle the amplification of that particular category of electronics.