As the folk duo Among the Oak & Ash, Garrison Starr and Josh Joplin do an exemplary job of updating Appalachian ballads on last year’s glorious self-titled full-length. Starr’s Mississippi roots show on such tunes as “Shady Grove” and “Hiram Hubbard,” which combine her full-bodied, fluent singing with minimalist bass lines and Joplin’s tasteful acoustic guitar. On “Peggy-O,” their voices mesh in a manner reminiscent of the classic collaborations of Sandy Denny and Richard Thompson in Fairport Convention. Like that great English folk band, Among the Oak & Ash never sacrifice spontaneity or rock ’n’ roll insurgency for mere reverence — the record features a marvelous version of The Smiths’ “Bigmouth Strikes Again,” which turns Morrissey’s tune into infectious Americana. Starr and Joplin may play at being folkies throughout Among the Oak & Ash, but they rock and swing with admirable intensity.