If his life depended on it, violinist Mark Feldman - once a Nashville country musician - could probably play Johnny Cash requests, which is more than you could say for most sharp-end jazz/ contemporary classical players who specialise in John Zorn's spikily capricious repertoire. But now he sounds as if he would be perfectly at home in the Kronos Quartet, and the music he makes with his Swiss pianist wife, Sylvie Courvoisier, is modern chamber-music with an improv bite.

At the Vortex, the pair played a double bill that also featured gifted Britons Richard Fairhurst and Tom Arthurs, on piano and flugelhorn respectively. The mood of the show, therefore, was intimately conversational - a dialogue of tonally-subtle shimmers and spacious piano rejoinders in the Englishmen's case, and often of fiery intensity from Feldman and Courvoisier.

The mellow, pure-toned flugelhorn note evaporating into silence that closed the first half and the fiercely slashing, urgently percussive dialogue with which the duo began the second effectively summed up the approaches of these two creative pairings. Feldman's rich, cello-like middle-register sound, keening high notes and pin-sharp fast flurries were pitched against Courvoisier's clackety prepared-piano effects at the start. The violinist then shifted into a harder-grooving episode that recalled Jerry Goodman with the early Mahavishnu Orchestra.

The awesome Courvoisier sounded like Mal Waldron and Cecil Taylor merged on tumultuous solo episodes of dark chords erupting to spine-chilling thunder, and the explorations of John Zorn's pieces typically joined classical quotes, jack-hammering noise, jaunty folk-dances, even a little Monkish jazz. The pair's own pieces bypassed Zorn's high irony content, often tenderly lyrical in Feldman's case, or erupting into fireworks of chattering melody, abrupt halts and total-piano expressiveness in Courvoisier's. It felt like three hours of music hammered expertly into one.