MUSIC / The time bandits: Robert Maycock reviews the Kronos Quartet at the RFH

WHEN they were younger, the Kronos Quartet made a name far beyond their native America for playing contemporary music as if they meant it. The group's apparently effortless virtuosity lifted difficult scores out of the usual dogged rut and revealed them to people they had never touched before.

Soon, the Kronos's flair for crossing boundaries within music too - playing Jimi Hendrix numbers and riding the fashion for minimalism - had made them big business on record. They cultivated a designer image. Now their London visits need the Festival Hall to pack in everybody who wants to hear them: rare for a string quartet and not the best way to feel the intimacy of chamber music, though they use amplification subtly enough to make up for it.

On Monday the playing and the sound had their usual finesse; few quartets can control a pianissimo nuance so devastatingly. The lights and the packaging were smart and restrained. But the programme unsettled more than it can have meant to.

It began with two short, touristy pieces from the current Pieces of Africa record, Dumisani Maraire supplying a tight set of teasing variations on a chord sequence and Hamza El Din a freer, Muslim-flavoured exercise in extending a melodic line.

Two British premieres followed, of which the Argentinian-born Osvaldo Golijov's Yiddishbbuk began with basic oppositions - wild howls and a quiet atonal chill, monkish restraint and writhing energy - and ended with a more sustained and cohesive intensity.

This still left a hunger for substance. Instead, at some length, there followed the naked emotion of Bob Ostertag's All The Rage. An angry and bitter text by Sara Miles was read over tape and quartet parts that derived from a recording of a riot by gays and lesbians in San Francisco last year. As an immediate, local reaction it might have been powerful.

But however sincerely motivated, the score was woefully thin and incidental. Why is one of the world's top quartets touring it? The piece crystallised a question that the evening's repertoire was raising, for this self-absorbed American whinge sat especially ill alongside jolly images of smiling Africans: nothing about Aids there.

Five minutes of Arvo Part, Summa, brought the theatrical contrast of an escape into medieval remoteness, with its typical prayer-like mosaic of reiterations. Real composing, real character, at last; but not enough of it. Nor was there in the concert's second half, which consisted of Henryk Gorecki's Quasi una fantasia. As so often with this enigmatic composer, passages of gripping, simple directness - the long opening lines over a pulsing cello, the fractured chorales and frantic speedings of the slow movement - sat at alongside crude gestures that might have been cynical or sarcastic or just badly judged. I don't know, the music seemed to say as it ended on a plain, unresolved clash of keys; you decide.

Everything in the concert came over as exotic, even the Gorecki, with its folk elements and its deliberate national colouring. Not once did the Kronos give the message: here's some music, listen and share it. For encore, they brought on the African singer Thomas Mapfumo and three instrumentalists and joined in with them. The Africans looked a bit bemused. This music needs a string quartet playing along like Mozart's G minor symphony needs a drum kit.

Some visitor from another planet, thinking the programme would give a useful update on the state of classical Western music, might draw an easy conclusion: the tradition is clapped out, and starting to be overrun by other, stronger cultures. But, hell, they know how to play.