On the surface, there isn't anything all that innovative about Evan Ziporyn's "Sulvasutra," which he wrote for the Silk Road Ensemble (though he wasn't sure he was supposed to tell us that.) But there's this guy, Sandeep Das, sitting in the center, who's playing tabla like he's in a trance, full of joyous abandon. Everyone else on stage (Brooklyn Rider, pipa player Wu Man,) have scores; Das learned the whole thing by ear. And feel. It's like a whole other thing, you know?