There are bluegrass bands, country bands, indie, hard rock and alt rock bands, roots bands, pop bands, blues bands, punk bands, dance bands, soul groups, jazz combos, chamber ensembles. Genres on lists as long as Kevin Durant’s arm. And then there are the Punch Brothers. Oh sure, their foundation, as it were, may be in bluegrass, usually with a “progressive” fronting it, and it’s a handy enough label when looking at their classic bluegrassian instruments: mandolin, guitar, banjo, bass, fiddle. And while bluegrass is a perfectly fine genre, the Punch Brothers bust through that label early and often in their concerts and albums,…