If jazz and rock are like a bickering, codependent couple, Tortoise are the faded memory of their promise and possibility. The Chicago quintet mixes the two genres without compromising either’s integrity, respecting the source material and rarely falling back on the music’s potentially harsh juxtapositions. Tortoise have weaved mellifluous lines in and out of complex time signatures and challenging arrangements over the course of 20 years and six albums. But even their most demanding songs leave fans with a tune on their lips. As the swooning guitar line in “Charteroak Foundation” (from their most recent album, 2009’s Beacons of Ancestorship) wraps around a driving rock rhythm, a counter-line dances wickedly, exposing the glimmering notes between the languid progressions. The result is a haunting polyrhythmic melody that’s just as impossible to hum as it is to get out of your head. That’s not to say everything the band does is progressive snobbery. “Prepare Your Coffin”’s glossy playfulness and “Yinxianghechengqi”’s snotty posturing are evidence of a band more focused on following the music’s lead than subjecting it to intellectual tinkering. It’s been more than a decade since Tortoise were crowned post-rock kings. They still manage to surprise and engage. Tortoise, with Brett Naucke, play the Grog Shop at 9 p.m. Tickets: $15. —Nick DeMarino
Review the show at clevescene.com/concertscene
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