PaPaJo is an acronym neatly hinting at the names of the trio's members, all giants of the European improv community � the German pair of trombonist Paul Hubweber and drummer Paul Lovens, plus British bassist John Edwards. The group first came together in 2001 and has reconvened regularly since, although this is only their third album release, following PaPaJo (Emanem, 2002) and Simple Game (Cadence, 2008). Issued to mark the group's fifteenth anniversary, the double album Spiela does not feature recent material but, as with those earlier discs, contains concert recordings, from Zagreb in May 2003 and Aachen in May 2009, lasting seventy-one and forty-four minutes, respectively.

Right from the opening track from 2003, "S C", one of the key ingredients of the trio's success is obvious: this is not a conventional trio of lead instrument plus supporting rhythm section but a symmetrical alliance in which each of the three plays an equal role with none of them leading or dominating the others. Each of them is an instantly recognisable voice with their own personal vocabulary and syntax, so it would be difficult to mistake them for anyone else. Those three individual voices manage to remain distinct as they combine into one collective voice. Without any of the three, the group sound and identity would be radically shifted and diminished.

Across nearly two hours, the music here is mercurial and defies easy pigeon-holing as much as the three individuals responsible for it. Improvised throughout, and constantly shifting, it has elements that will keep jazz fans returning time and again for more. But the group ethos seems based upon unpredictability and risk-taking, so anyone hoping to settle down into a comfortable groove is in for a few surprises along the way; time and again, the three abandon any semblance of jazz and veer off into passages of freely-improvised noise, only to reverse the process just as unexpectedly. That is achieved without any disconcerting non-sequiturs or shocks, in fact with an admirable sense of logic that is sure to carry listeners along with them. Given the quality of PaPaJo's music, three releases in fifteen years seems far too few. We must hope for more, and for more recent examples of their work. Meanwhile, Spiela is a release to savour.