Saxophonist Chris Potter's four- piece Underground has been one of the most listened-to small groups of the past decade. They blend explorative writing with virtuoso improvisation from some of the most articulate voices in contemporary jazz, including pianist Craig Taborn and guitarist Adam Rogers, not to mention the leader's peerless saxophone playing. Now he takes the Underground formula and swells it to an 11-piece orchestra, adding Steve Nelson's vibes, electric and acoustic bass, and a string quartet led by violinist Mark Feldman. There may not be quite the same levels of agility, but the essential nature prevails – an artful integration of Potter's different influences from Bartók to James Brown – as it reaches towards a category of its own. propermusic.com