Youthful a cappella group Pentatonix gave it their all and wowed the crowd on 'The Sing-Off' (Mon., 8PM ET on NBC) last night. The Los Angeles-based group performed their unique take on Katy Perry's song 'E.T.' and afterward seemed real happy with how i more

THE SING-OFF  Season 3 episode 2 airs Monday September 26 at 8-10 p.m. ET on NBC. The Sing-Off  Show Synopsis:  The second set of eight groups perform together and individually for the judges with the hopes of being named the a cappella cha more