Sufjan Stevens dropped by WNYC to sing “Pleasure Principle” the last acoustic portion of his 25-min long epic “Impossible Soul,” from his even more epic album Age Of Adz. He’s joined here by The National’s Bryce Dessner and two members of his band, including Kat Martino. Sufjan is ending his so-called touring behind this record next week with two big shows at Prospect Park, which is shame because this material deserved more of a showcase on a fuller national tour.