Sufjan Stevens' haunting whisper belies his massive ambitions. Starting in lo-fi folk, the Detroit native has since attempted to encapsulate each US state with a record, dabbled in classical composition and experimented with sprawling electronics. The singer-songwriter is arguably at his best when he's at his most personal, none more so than on '15's Carrie and Lowell, an autobiographical collection of songs inspired by his mother's passing.