In the tightknit musical community of Austin, Texas, it’s tough to get away with posturing. You either bring it, or you don’t. If you do, word gets around. And one day, you find yourself duetting with Bonnie Raitt, or standing onstage with the Allman Brothers at New York’s Beacon Theater and trading verses with Susan Tedeschi. You might even wind up getting nominated for a Best Blues Album Grammy — three times in a row.