Bass-music big-timer SBTRKT returns to Williamsburg for a live set of R&B-kissed low-end action, with rapidly ascendant Chicago singer-songwriter-polymath Willis Earl Beal lending support. The Sepalcure duo, Praveen "Braille" Sharma and Travis "Machinedrum" Stewart, open up with a set of gorgeous dubstep-not-dubstep rhythms.