Jessica Hernandez & the Deltas(Photo by Johnny Nevin) There's a band out of Detroit called Jessica Hernandez & The Deltas, and just about everybody who sees them thinks they're seeing a promising new group with a cool new singer, but that's not quite all of it. When you take a good look at Jessica Hernandez & The Deltas you can see a lot more than just that, because what you're really seeing is an exorbitant take on where music can come from, an all-embracing vision of what music can be. You're looking at a stage full of gifted young jazz