Over the past few years, St. Louis has been blessed with bi- and tri-annual concerts by the Denton, Texas, combo Centro-matic. The quartet's visits always bring plangent guitars, serpentine drumbeats and a few from-the-heart moments of beauty. And while the band's shows are always worth checking out, this week's appearance is a must-see: Centro-matic will play its own set and then transform into its rarely seen alter ego, the largely acoustic and down-tempo South San Gabriel. SSG albums tend to replace Centro-matic's volume with more ambient, sculpted sounds and a reliance on big drums with a relaxed patience. The timing of this co-headlining tour makes sense, as this year's double-disc Dual Hawks combines albums by both bands and lets listeners hear the twin sides of singer Will Johnson's psyche, a singer whose songwriting can devastate and amaze regardless of the setting.