Straight No Chaser is performing Thursday at Mohegan Sun Arena. Then, Pentatonix takes to the Sun stage on Dec. 22.

Here’s what I would like to see: both of these talented a cappella groups onstage together, dueling like something out of “Pitch Perfect.”

But that is not to be, so everyone will have to content themselves with separate shows.

This year happens to be Straight No Chaser’s 25th anniversary. The ensemble formed as a student group at Indiana University in 1996. In 2007, they hit the big time when their 1998 video of “The 12 Days of Christmas” went viral, and the founding members of Straight No Chaser signed a record deal.

Their gigs bubble over with clever new voice-only version of tunes like “Proud Mary” and Queen’s “Don’t Stop Me Now,” and this time of year, they also bring out the Christmas songs for a harmony-happy holiday.

Straight No Chaser, 7:30 p.m. Thursday, Mohegan Sun Arena; $30; mohegansun.com.