The xx, jj, Nosaj Thing

The xx are a band that, live and on record, captivate your attention with the fewest moving parts possible: spare but soft-knocking beats, faint keyboard echoes, guitar and bass sounding single notes at a time—no chords, only negative-space melodies. Over these deceptively skeletal songs—lush R&B by way of austere post-punk—Romy Madley Croft and Oliver Sim trade hushed, intimate vocals. Onstage, they communicate in minute gestures: Jamie Smith busily tapping on his sampler, Croft and Sim swaying imperceptibly. They don’t move much, but every move they make is riveting. (Showbox Sodo, 1700 First Ave S, www.showboxonline.com showboxonline.com. 8 pm, $20, all ages.)