Listening to Into the Cauldron, a collection of mandolin duets by Mike Marshall and Chris Thile, can be a frustrating experience--in the best possible way. It's definitely not the playing. Marshall, a veteran of such seminal acoustic bands as the David Grisman Quintet, and Thile, the mandolin wunderkind of Nickel Creek, sound better than ever. No, the problem is in the variety of styles on display. After hearing Marshall and Thile dance across the strings on "Fisher's Hornpipe," you'll wish this CD was a collection of fiddle tunes. When they trade licks on "Scrapple from the Apple," you long for more bop tunes. Their too-brief version of one of Bach's Goldberg Variations only whets your appetite for a mandolin version of the complete composition. And the duo's original tunes seamlessly blend elements from all of these styles, and more, as if mixing James Brown's rhythms, Bill Monroe's melodies, and Stravinsky's harmonies is the most natural thing in the world. Listening to Into the Cauldron is frustrating because it's only one CD, and Marshall and Thile obviously have more than enough musical ideas to fill a dozen more. --Michael Simmons