The concept is great: Liberate bluegrass' hot-shit riffing and blue-sky harmonies from its hidebound formalism and see where it flies. It's turf explored by the Dead and others. But while this Boulder, Colorado, crew brings dazzling chops to the table, the songwriting is less memorable. The high-lonesome stuff works best (the melancholy hoedown "Rain Still Falls"), and "Isolate" is a minimalist...