There are 3 main ways to set up the audio tuner with the TV.
The main input (Cable connection/ HDMI) goes to the TV. The headphone output would give a stereo output which you may connect your audio tuner. This is a stereo out and will mute the TV.
The output from a DVD player. The Video (yellow) goes to the display, Right (red) and Left (white) audio to your audio tuner.
Directly connect your source to audio tuner via HDMI. Modern day audio tuners have audio filtering and video out on the tuner. On the tuner, connect HDMI IN to your source and connect HDMI OUT to your TV.