North Carolina musicians Scott and Seth Avett took a road trip to Cleveland several winters ago to play a chilly set at the Barking Spider saloon. The brothers played traditional instruments associated with bluegrass, but the music was an energetic amalgam of country, pop, and rock. The Avett brothers have been back to Northeast Ohio a number of times since, each time playing bigger venues. They’re building a national buzz for their enthusiastic musical style… and their new CD was masterminded by heavyweight producer Rick Rubin. ideastream’s David C. Barnett has this appreciation.