Mannheim Steamroller is a music group founded by Chip Davis, and co-founded by Jackson Berkey, known primarily for its modern recordings of Christmas music. The group has sold 28 million albums in the U.S. alone. In 2008, Chip Davis underwent surgery which prevented him from touring or performing with the band. Rather than force the tour to stop completely while he recovered, Davis opted to hire additional musicians to temporarily replace him. He also decided to create two different lineups of the band, one of which toured in the Midwest, the other on the East Coast.