Music KRONOS QUARTET / PHILIP GLASS Shepherd's Bush Empire, London

John Zorn's The Dead Man opens with what could well be sounds of disembowelment, and ends with a movement where the players use their bows to flail the air like carpet-beaters, creating a dust-storm over the stage. In between come loony-tunes of frantic cartoon music, like the Goldberg Variations in MTV-time. After that, Philip Glass sounded easy, even quaint.

The composer began proceedings, looking rather like an elegantly rumpled talk-show host, by giving a concise introduction to the format of the programme - two sets, with him as the support act in each. He then played two short Etudes at the piano, a lyrical, Debussy-like pair that suggested, as with latter-day Michael Nyman, that Glass is really a bit of a softie at heart. Certainly, it was difficult to square the full-on minimalism of his earlier works with the delicacy of the Etudes and the later string quartets (Nos 4 and 5) performed by Kronos. Deprived of electronic keyboards and wind assistance, the pulse of Glass's music sounds less like the soundtrack to a brain-scan than the grounding for a deeply nostalgic evocation of the past.

Kronos, by contrast, were hard as nails (except when playing the Glass quartets). After the brilliant Zorn opener, they performed Two Greek Studies by the eccentric American composer Harry Partch before dispatching the Fourth Quartet, a slow and doomy piece written in memory of the artist Brian Buczak, who died of Aids in 1988. Now that waistcoat-abuse and trouser- crime have infected much of the contemporary classical community, Kronos look less unusual than one had hoped, although the leader David Harrington's shirt might possibly have earned a place in the wardrobe of the mid-Sixties Troggs. These days they are iconoclastic only in their music, and the over-styled Philippa Starck-like chairs they choose to sit on.

They opened their second set with Raymond Scott's Dinner Music for a Pack of Hungry Cannibals, a piece that lived up to its title by continually picking at the bones of old popular songs, country fiddle music or Hot Club-style jazz. But the real thrill of the night was the following Elvis Everywhere by Michael Daugherty, which featured the taped voices of three Elvis impersonators as the libretto to a fiendishly complex commentary on a classically American obsession. Although Kronos do raise questions of gimmickry (as in the truly dreadful thrash-metal encore, chosen when they couldn't, ahem, find the score to Glass's Company quartet), the Elvis piece was a stunner, recalling Steve Reich's early works with voices, but to much greater effect.

The impersonators' repertoire of early, mid, and late incarnations of the King had been cut and layered into a digital palimpsest of iconic slogans, "bay-buhs" and "uh-huhs", accompanied by quite astonishing shifts of metre by the quartet. After that came Quartet No 5, reassuringly formal and precise, but also, clearly, a blast from the past. One suspected that Kronos had chosen their programme to spotlight themselves rather than Glass; if so, they notched up an emphatic victory.