4-man, 1 woman Pentatonix, or PTX, are vocal sensations and winners of season 3 of NBC's The Sing-Off, who are pushing the instrument-free envelope. Named after the 5-note musical scale, this quintet has paired their intricate arrangements with brilliantly re-invented pop songs. Lead vocalists Scott, Kirstie and Mitch, bass Avi and beatboxer Kevin, all Southern Californians in their early 20s, got together to audition for The Sing-Off, and created a sound and style that are unique and deliciously infectious! "Volume I" is 6 tunes, "Starships" is a techno pop rhythmic dance tune with salsa and hip hop flavors, and one of the most danceable a cappella tunes we've heard; "The Baddest Girl," written by the group and Ben Bram is a complex, driving, rhythmic torch song, and "Somebody That I Used to Know" by Luiz Bonea and Walter de Backer is a poignant, memorable tune about a former love. Cut 4 is a wonderfully-arranged cover of Imogen Jennifer Jane Heap's "Aha!" that keeps on coming with powerful beatboxing and intertwined rhythms, and "Show You How to Love" is another sweet group original with a top 40 hook. "Love You Long Time" by Salaam Remland and Jazmine Sullivan is a powerful, driving love song. Bottom line: Pentatonix is re-inventing a cappella all over the place, they're one of the hottest vocal bands on the planet, and "Volume I" is one of the best of the year. Enough said!