The Arlington group Pentatonix hopes to make it big on NBC's "The Sing-Off."
Mitch Grassi, Scott Hoying and Kirstin Maldonado grew up performing at Theatre Arlington, which hosted a watch party attended by their family and friends.
Todd Hart, executive director, said he knew it was only a matter of time before the trio made it big.
"They're all three individually amazing musicians, and when you put them together, they're crazy," he said.
Hart said the trio flew out to Los Angeles earlier this year to audition for the show. However, producers told them they needed at least five people to make a group.
Hart said the teenagers went on YouTube and found beat-boxer Kevin Olusola and bass Avi Kaplan.
"When they came out here to film all their backstory stuff -- I had not really heard the group sing before," Hart said. "They blew me away. ... And I don't get blown away that often. I was really amazingly dumbfounded."
Pentatonix made it through the first round of "The Sing-Off," performing Katy Perry's "E.T." Hart said he has no doubt the group will make it to the finals.
"It's really interesting -- a lot of acapella groups have one front person and the rest of the backup," he said. With this group, anyone can step out at any time and be a star. It's really cool."