It’s one thing to work up an excellent imitation of your musical idols. It’s another to find your own voice. Wimberley mandolinist Sarah Jarosz hasn’t quite made the leap across that chasm, but she’s closer to the other side than any other twenty-year-old out there. Two years ago, she turned a lot of heads with—and earned a Grammy nomination for one of the tracks from— Song Up in My Head , a debut album intent on demonstrating that she was more than just another acoustic prodigy. (Covering Tom Waits and the Decemberists helped.) Her sophomore effort, Follow Me Down (Sugar Hill), is even more impressive, especially considering that Jarosz has yet to become a full-time musician. Her debut was released around the time of her high school graduation, and she’s since enrolled in Boston’s New England Conservatory of Music. Yet there’s no music school wankery on hand. Showing restraint and taste, Jarosz delicately weaves together adventurous song structures, Middle Eastern leanings, and a reverent cover of Radiohead’s “The Tourist.” Incorporating a newfound appreciation of music outside her idiom, she’s brought even more depth to her roots-based songs. A trio of compositions (the folky dirge “Annabelle Lee,” based on the Poe poem; the tricky, expansive “Come Around”; the melancholy “My Muse”) are the best of her short career and make you yearn for the day when she’ll strip away the Nashville ear candy production and push her talent even further.