The MGMT Co.’s Jonathan Kalter was visiting family in Florida when his father insisted he watch not just a Pentatonix video on YouTube – but 13 of them. In one sitting.

Shortly after, a friend at Epic Records called him to say the group was a runaway favorite on “The Sing Off” and asked if he’d like to take a meeting to discuss managing them.

Kalter couldn’t say no.

The five singers who make up the vocal group Pentatonix – Scott Hoying, Kirstie Maldonado, Mitch Grassi, Avi Kaplan and Kevin Olusola – ended up winning “The Sing Off” and are well on their way to mainstream stardom.

Photo: Esther Kaplan

In addition to viral videos of “The Little Drummer Boy” and a medley of Daft Punk covers that alone has garnered more than 56 million views, the group has made the leap from performing in 500- to 1,000-seat venues to selling out some of the top theatres in the country including two at the 1,970-seat Orpheum Theatre in Los Angeles.

“Pentatonix were so different and so evolved as a spectacle. When they came off [“The Sing-Off], there was a real intrigue to them based on the fact that they were doing something that shouldn’t be possible for an a cappella group,” Kalter told Pollstar.

He knew he had a short window to prove his charges could be successful as a touring act and set out to book them in mainstream venues, with an affordable $20-$30 ticket price.

Photo: Andrew Ryan Shepherd

“We really did make an effort to pick venues that any developing band would choose to build a touring career,” Kalter said.  “A lot of the venues we’re playing are ones I’d put my singer/songwriters or rock bands in, so we weren’t pigeonholed as a niche a cappella group.

“The only thing a cappella about them is they don’t have instruments. It doesn’t look or sound like an a cappella show. The show now is 90 minutes, with lights and risers and more staging, movement and choreography. It’s a real show and experience for everybody, with audience participation and anything that you would expect from a pop show outside of multiple wardrobe changes,” Kalter explained.

Pentatonix recently launched its latest tour, which runs through April, before heading to Europe.