Hilary Hahn loves to upset expectations, which is why she's recorded both Bach and Schoenberg. But her improvised collaboration with composer and prepared-pianist Hauschka -- who often plays to indie crowds -- could surprise those who think they know the violinist's range. Rehearsing off-and-on for two years before this recording, they developed a language that keeps the jam sessions from being free-for-alls; the payoff of "Adash" and the suite-like "Godot" could pass for composed. Still, there's a hint of wildness throughout this, one of the more striking instrumental albums in recent memory.