The world-class contemporary sax colossus Chris Potter seems to be something of a late bloomer in terms of his recordings as a leader. Proof is in his Underground Quartet's explosive avant jazz Uberhang in 2010 and his superb debut for ECM The Sirens, released at the end of 2012, that reveal him stepping up a few gears. Potter now releases his second album for ECM with a set of compositions initially written for a performance at the Lincoln Center for which he has formed an extended version of his electric funk Underground band, although there is less of that ensemble's crunching New York avant-groove here. The quartet is augmented by a rhythm section that includes two bassists and the outstanding vibraphonist/marimba player Steve Nelson, Potter's bandmate in the early Dave Holland quintet. But the major new ingredient is a string quartet, which includes the John Zorn associate Mark Feldman. Potter starts things off in a more conventional manner with the strings on the opener ‘Lament’ slotting into a backdrop role supporting a gorgeous sax theme. But the core of the album is the four movement suite ‘Imaginary Cities’, and that's when Potter's writing for extended ensemble becomes more inventive: pizzicato strings sound kora-like on the African grooving ‘Duality’ with a captivating marimba solo by Steve Nelson. ‘Disintegration’ starts with a written contemporary classical-influenced ensemble passage that could be a collective free improv session. If it's a less focussed album than The Sirens, the elegant arrangements and ensemble performances are first rate and it slowly reveals more layers on repeated listening.