Arditti Quartet, Queen Elizabeth Hall, London

This second concert in the on-going London retrospective of the work of the late Luciano Berio was prefaced by a valedictory, but also inspiriting filmed interview he gave weeks before his death last May.

This second concert in the on-going London retrospective of the work of the late Luciano Berio was prefaced by a valedictory, but also inspiriting filmed interview he gave weeks before his death last May. Asked whether he shared the fashionable pessimism about the future of classical music, the visibly ailing composer replied, "I am not afraid...there are certain deep, solid roots in what we do that cannot be destroyed." It was a remark that epitomised the comprehensive humanism of his outlook; explaining why he felt freer than most in the post-war avant-garde to return repeatedly to that apparently traditional medium the string quartet.

Not that any of the four quartets he produced at intervals is exactly traditional in approach. The earliest of them, entitled simply String Quartet (1956), with which the Arditti Quartet opened this survey in a razor-sharp reading, was very much in the minuscule, dryly fragmented post-Webern idiom of its period. Yet even then, Berio could not resist teasing his more poker-faced confreres by insinuating the odd, fleeting tonal chord.

By contrast, Sincronie (1964), which concluded the first half, was a study in what the quartet could do if its contrapuntal propensities were disregarded. Here the four players tend to do everything as an entity - switching between bizarre pizzicato textures, frantic flurries, stark unisons, and so on. Not even the snapping of leader Irvine Arditti's A string and coming adrift of his chin-rest could break the performers' fierce concentration.

Yet Berio's quartet masterpiece is surely Notturno (1993), a continuous, muted 25-minute span in which, beneath the most quicksilver frissons and flights of figuration on its surface, one never ceases to be aware of a slower undertow. Glosse (1996), placed second in this concert, comprised, according to Berio, the shards of his failure to write a fourth quartet. But its 11-minute span comes over quite as much as an oblique gloss on Notturno itself. Between Sincronie and Notturno, the Arditti Quartet's cellist, Rohan de Saram, gave the UK premiere of the final version of Sequenza XIV (2002-03) which Berio composed especially for him. This opens, in homage to de Saram's native Sri Lanka, with an explicit evocation of Kandyan drumming in left-hand pizzicati and right hand tappings on the belly of the instrument.

And, unlike some of the earlier solo Sequenzas, which tended to concentrate on one narrow technique to the point of perversity, Sequenza XIV develops a wide-ranging dialectic between bowed phrases of various lengths, pizzicato punctuation and periodic returns of the drumming. The noble authority with which de Saram imparted this 13-minute virtuoso discourse drew an intent audience's warmest response.