Sō Percussion is a four-piece New York-based percussion quartet who have been collaborating with Pulitzer and Grammy-winning composer and vocalist Caroline Shaw for over a decade. At Big Ears they performed their theatrical evening-length show built around the album "Rectangles and Circumstance", opening with Shaw alone under a spotlight and gradually adding marimba, vibraphone, steel drums, flowerpots, drums, and found percussion. I saw them perform three times over the weekend, including an hour-long trance-like performance of Steve Reich's "Drumming".