When not playing with Wilco, drummer Glenn Kotche expands into contemporary classical territory with pieces like these, written for the new music stars So Percussion. With the exception of the potent “Drumkit Quartet 1,” the works, written for all manner of percussive instruments, are less aggressive than Kotche's chamber compositions from a previous set, Adventureland. What the pieces lack in grit they make up for in charm: Just see the playfully varied rhythms that run through “Drumkit Quartet 51,” a composition textured enough to merit two very different interpretations, which bracket the album.