I have a lot of sympathy for acoustic folk duos. Standing out when your only tools are your own voices, some guitars and perhaps a mandolin or banjo is a tough task. But The Honey DewDrops make it work. Their melodies are clean and crisp, restrained in a way that never stalls momentum. Their voices make the tunes remarkable. Kagey Parrish sings like a rough wind; think Willie Nelson with deeper resonance. Laura Wortman possesses the piercing clarity of Dolly Parton, but her lower range is a fitting complement. The South Carolina Broadcasters, an old-time outfit from Palmetto land, open the show with beautiful harmonies of their own. —Jordan Lawrence