It's been a long time since the music of either Chick Corea or Gary Burton has been called "difficult." Although Burton has maintained a reputation as a gifted traditionalist working on a rather nontraditional instrument (the vibraphone), most of Corea's work since the late '70s has been the very definition of the pallid, synthetic smooth jazz that makes even the mildest jazz snob crinkle his nose in disgust. There have been moments, though, in which both artists have displayed the spark that enlivened their early work. This particular tour, on which Corea and Burton revisit their groundbreaking 1973 duet album Crystal Silence, promises to provide some of that spark. Though muted in tone, Crystal Silence was the first of several phenomenal collaborations between the two and stands today as one of the finest discs to emerge from the ECM label's early days.