James Ginzburg and Paul Purgas are getting crustier and more experimental with every passing year. Recur, their fourth full-length excursion, is decidedly fuzzy and discordant. Seemingly intent on pushing experimental electronics to its limits, the formerly Bristol-based duo serve up a challenging but rewarding set based almost entirely around half-rhythms, white noises, drones, feedback and hissing atmospherics. It’s spooky, intense stuff, all told, occasionally enlivened by sparse, pared-down concoctions that sound like a smacked out take on Autechre. But for all the bleak, out-there sounds, Recur is strangely involving, due in no small part to its immersive nature.