Although this summer marks its sixteenth anniversary, Don Caballero still functions as a start-up band. Troubled from day one by its members' combustive personalities, the seminal Pittsburgh math-rock group fell irreconcilably apart in 2000. But as it turned out, the "breakup" was more a chance for drummer and founder Damon Che to regroup outside of his old sidemen's bad mojo. Still, Don Cab's internal tension helped to produce some of the past decade's most bracing instrumental rock, and when Che re-established Don Cab in 2003 as himself and three youngsters (from Pittsburgh's Creta Bourzia) who'd clearly gotten their best moves from his band, some fans turned their backs. Unfortunately, these fans missed last year's World Class Listening Problem, which finds Che & Co. not just revisiting Don Cab's darker, heavier salad days, but also adding weird new layers of complexity and occasional flashes of brilliance to the band's formidable musical legacy.