Perelman's lack of compromise and the faith shown in him by Leo records is such that he can fulfill a project of this scale: a six-volume series exploring improvisation in trios of differing configurations. With drummer Gerald Cleaver joining him on five of the sessions it can also be said that this batch of music demonstrates their strength as a duo that can significantly shift shape when joined by a third player. For example, the presence of Karl Berger, playing piano rather than vibraphone, leads to work of a considerably different hue (Vol.1) to that which is produced when Matthew Shipp steps in (Vol.3). The presence of bassists as individual as William Parker and Joe Morris also ensures that the contrast between the music produced by two sessions using the same set of instruments is marked. But the whole point of freely-improvised music such as this is the strength of character of the players, their ability to listen, respond, react, retain a sense of self, yet meld into an unpredictable ensemble voice. Perelman has developed his inner circle of collaborators over many years and the communication between them is now advanced, which is a double-edged sword. At times they can trade a touch on an established vocabulary that lacks a sense of daring, but they still manage to enter some thrilling pockets of sonic newness where the masterful control that Perelman has of both legato and fortissimo phrasing, his timbre practically a mutation of harp, whistle and laser-synthesiser, comes into its own, especially when entwining with Mat Maneri's ferocious viola (Vol. 2). The wide range of ambiances and sensibilities, or rather landscapes, from the meditative undergrowth of the Berger disc to the volcanic explosions of the Morris set (Vol. 6) remains the strongest card in Perelman's hand. Challenging, unrelenting, rewarding.