The Avett Brothers

The reigning kings of crossover bluegrass are without a doubt the biggest folk-rock success story in recent memory, and to a great extent the most interesting in that this time it's not just about acoustic guitar singer-songwriter types – one of the titular brothers focuses on the banjo, and upright bassist Bob Crawford and occasional cellist Joe Kwom figure prominently among the project's engines. After nearly a decade of toiling away in relative obscurity (at least outside of passionate regional acclaim in their native North Carolina), their 2007 sorta-smash Emotionalism drew the attention of legendary producer Rick Rubin, who brought them into the major label game for last year's improbably even more heartbreak-prone I And Love And You. Grace Potter and the Nocturnals open.