The Punch Brothers are an acoustic band with a sound that defies most descriptors. They're playing this weekend as part of the Ellnora Guitar Festival, and two members of the group, Chris Thile and Noam Pikelny, spoke with Illinois Public Media about how they describe their sound, solo projects, taking over for Garrison Keillor (in Thile's case) and, in Pikelny’s case, coming back to play after graduating from the University of Illinois.