Airs Thursday, April 17 at 8 p.m. In the musical movement known as roots revivalism, there are musicians indebted to and enamored of their form and its forebears, who occasionally succumb to simple imitation. Other times, there are artists fearful of being mere imitators, who sometimes produce forced and gimmicky musical hybrids. And then there are musicians that are respectful of American musical tradition, but not restricted by it., who combine centuries' worth of musical influences with an emotionally tough, undeniably modern songwriting sensibility. Such is the case with the all-female bluegrass group Della Mae, whose 2013 performance at the Savannah Music Festival is featured in this episode.