Samba Jean-Baptiste ’s music dwells in the semi-sublime state of being bored and stoned. On his second album, +3 , he floats across faint guitars, zonked reverb, and avant-rap and R&B production spiced with capricious experimental interjections. Even the signs of urgency, like barking dogs and sirens, sound glazed over; everything comes shrouded in an indica plume. Beneath the album’s apparent drift lies Jean-Baptiste’s almost classical concern for proportion and structure. Jean-Baptiste, who trained as a cellist, arranges his songs—some of which are barely over a minute long—like a chamber cycle punctuated with interludes. Despite the fog, +3 represents a clear tightening of Jean-Baptiste’s practice. His previous album, Cardinal , was guided by charmingly disorganized instinct. Here, his stabs at form feel more purposeful.…