The singers in Pentatonix, who open for Kelly Clarkson Tuesday in St. Paul, scour YouTube. The group's beatboxer, Kevin Olusola, is taken by Swedish trio Ember Island's version of "Where Are U Now," the hit by electronica duo Jack U.

Jon Bream

"It's so beautiful. They took it and stripped it down. The beginning reminds me of Imogen Heap. That's something we as a band love because a lot of our music is polyphonic."