DENNIS BRENNAN has been acclaimed as one of Boston’s best singer-songwriters for longer than most locals can remember. The music on Brennan’s many albums falls loosely into the Roots Rock/Americana category, but his songs have always been clearly influenced by his deep and esoteric love and knowledge of Blues and Soul music. For a few years now Brennan has held down a weekly dive-bar residency with a brilliant band of simpatico players dubbed “DENNIS BRENNAN and the WHITE OWLS,” just to celebrate and explore their take on the blues.