These essential figures of country music history have become fairly regular tourmates now, and that’s great because it’s a wonderful double bill that offers a sweet look at just how honest, raw and damned different country music can be. Willie is, of course, the chairman of the board. He’s the real deal — a genuine outlaw who has had his brushes with the law but is still here to sing about them. Like Bob Dylan and Neil Young, his voice is an acquired taste, but he’s one of the great American songwriters. Krauss, meanwhile, has a voice that can tame wild beasts. There’s nothing polished and rhinestone-y about this incredible artist from the bluegrass world. They’re two of the greatest living country artists, and they’re performing at the same show. Incredible.