It would be easy to write off Los Angeles-based Cafe R & B as just another blooze-rock outfit were it not for their vocalist, Roach, whose rich soprano can ascend in a heartbeat from a mewl to a whorehouse mama’s bellow without sacrificing accuracy or nuance. Her purrs smolder with pent-up power; her midrange belting is whiskey-coarse but unerringly melodic; even her most audacious upper-register shrieks sound unforced. Like a jazz singer, she often sounds as if she’s thinking in terms of triplets: even when she’s bucking a thunderous shuffle or rock ‘n’ roll boogie, she’ll dip insinuatingly into whatever spaces she can find between the beats, then grab on to the rhythm again and ride it, wailing and testifying, to its conclusion. Lead guitarist Byl Carruthers and the band have tempered their excesses on their most recent release, Blues and All the Rest (ItWorks Music, 2002), and Roach sounds more torrid than ever. The most riveting track, “Something Down,” is a country-folk lament with Memphis overtones that masterfully invokes the existential displacement that comes with true heartbreak. Roach’s voice starts out silky, slowly acquires a wounded edge, and ultimately explodes into a wail of desolation past caring. Doug McDonald opens. Friday, March 26, 9 PM, Buddy Guy’s Legends, 754 S. Wabash; 312-427-0333.