Must listen: Kid quartet covers Katy Perry's "Firework"

This is the Joyous String Quartet performing a cover of "Firework" that's off the hook. The auspicious long-time bosom buddies (they've been playing together since they were four!) are currently blazing their way across the internet. You might recognize the little maestro on the cello, Justin Yu.

He performed on Ellen Degeneres last September to the delight of the audience and viewers around the world. The masterful bobbing of his head and swift picking of his fingers is mesmerizing! Check him out on Ellen below:

Want the Joyous String Quartet to marvel you some more? Visit their YouTube channel, Joyous Music School.