If you are outdoors and need better quality sound and have rubbish car speakers like me, but better digital sound exterior speakers, it comes in useful for audio out .
Same as i do at home. By plugging my hifi surround set into the aux of my sky box ,and selecting aux on the hifi, i get TV audio quality through my digital surround speakers, located all over the house. Much better than the TV sound so i just turn the TV volume off