Audience members at the National A Cappella Convention thought they knew what to expect when Cluster, a group known for its supreme take on vocal jazz, walked on stage Saturday night in Memphis, TN.

Soprano Letizia Poltini and alto Liwen Magnatta treated the crowd to a rendition of "Le nozze di Figaro," but when the rest of the band joined in, the group's performance transformed into something entirely different.