Pentatonix is an amazing group, elevating acapella from the novelty of Straight No Chaser (no stranger to Christmas themselves) and Rockapella. They’re kind of like a group of Bobby McFerrin. Most of their songs are covers, but sometimes they do come up with their own thing. From their latest Christmas album, here they are with an original song, “That’s Christmas To Me”.
There’s more Christmas and non-Christmas music on their official YouTube page.