Mandolin god Chris Thile - former and current leader of Nickel Creek and the Punch Brothers, respectively - is generally known for kicking bluegrass forward: Check out his down-home covers of Radiohead’s "Morning Bell" and Pavement's "Spit On A Stranger." This ridiculously blazing set with hot-shit Brooklyn guitarist Michael Daves, recorded at Jack White's Third Man studio in Nashville (where they also cut a 7" single with White, "Man In The Middle/Blue Night"), focuses instead on old timey material by Bill Monroe, Lester Flatt, and others. Dusty museum pieces they’re not: The uptempo jams are wild-picking shred fests, and the ballads cut deep. On a soulful reading of the traditional "Rain and Snow" (a Grateful Dead staple), the pair’s high lonesome harmonies are hollered up like pleas from the depths of a coal mine. That’s a place these city-slickers have probably never been. But no doubt they understand the rock-bottom blues.

Listen to "Rabbit in the Log":

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“Help Me”

Joni Mitchell wrote and recorded this song for her album Court and Spark, but she had to switch from her regular band to make the song sound exactly the way she wanted. "I had attempted to play my music with rock & roll players," she told Rolling Stone. "They’d laugh, 'Awww, isn't that cute? She's trying to teach us how to play.'" Mitchell switched to a jazz band, Tom Scott’s L.A. Express, and scored the biggest hit of her career in the process.