There are plenty of new music ensembles wandering the classical music world, but few ever manage to achieve serious longevity or catch on with any measurable percentage of mainstream listeners. But after ten years of diligently honing their craft and cultivating audiences with a unique blend of high energy and disarming informality, the sextet of young musicians known as “eighth blackbird” are knocking on the door of new music success previously known only by the Kronos Quartet.