Module Voice Image

You know Christmas is here when smash-hit a cappella group Pentatonix does a cover of “Carol of the Bells.”

The singers, who vaulted to stardom after winning the third season of “The Sing-Off” on NBC, cover of the Christmas classic has garnered more than 11 million YouTube hits and more than 21,000 comments.

“Among their covers, this one is one of my preferred,” said one YouTube user.

Another user equally enjoyed the group’s cover performance.

“Loved them the first time I heard them on The Song Off. Now, PTX plus Christmas songs — wonderful experience. They’re like nothing else out there,” said YouTube user Terry Hines Thursday.