Dolly Parton's ''The Grass Is Blue'' was '99's top bluegrass album, but Little Sparrow, her all acoustic follow up, proves a sequel can surpass the original. In wedding bluegrass with the Appalachian sound of her youth, Parton, who wrote half of the material and reprises her classic ''Down From Dover,'' repeatedly explores her favorite theme -- romantic betrayal -- and turns in a powerful performance, augmented by the best of bluegrass' hot pickers.