Taraf de Haidouks, Lyric Hammersmith, London

Incredible string band

Two nights to go before Taraf de Haidouks leave London and sweep on round the world. Catch them quick or repent at leisure, because they're now at their peak, and ­ given the advanced age of some of their members ­ they won't last for ever. A taraf is a Romanian village band; haidouks are brigands; the de merely denotes the fact that their "discoverers" were Belgian. But the name has come to signify the quintessence of Balkan musical fire.

They look oddly at home on Frank Matcham's ornate Edwardian stage, plonking down their gear as though taking a break in a garage. First up are two violinists, a flautist and an accordionist, plus backing-players on bass and cimbalom. Little puffs of rosin rise round the fiddlers' heads as they whirl into the opening piece, in which each virtuoso gets his moment in the limelight ­ not forgetting the bassist and cimbalom-player ­ without disturbing the seamlessness of the whole.

Then it's a singer standing to attention in a drab grey suit, but what comes out of his mouth could not be more extravagant. He begins on a long high note and then descends in a series of laughing gulps; his voice is soft but penetrating. You realise with astonishment that he's not mic-ed, and then, with equal astonishment, that you're grateful for having to listen. Last year, in Ronnie Scott's, this band were deafeningly mic-ed, but here you can savour the subtlety of their sound.

I have all the records and thought I knew all this band's tunes, but their repertoire seems inexhaustible, their variations infinite. What's constant is the contrast between the surface frenzy and the underlying calm, as the music modulates through the keys; no wonder they've become jazz heroes. The show is a gorgeous blur of sights ­ flying hammers, fingers flickering over keyboards ­ and sounds, as solo after solo takes off above the sweet miasma of the cimbalom.

A lot of jokes are tossed to and fro between the singers, but it's their venerable leader ­ toothless, just skin and bone beneath his baggy beige suit ­ who gets the biggest laughs with a tuned farting noise he creates from a loose string on his violin. When he sings, you have to strain to hear, but his instrumental tone is strong and true.

A disappearing world? No, because the most dazzling players are still in their thirties. But a cheerfully opportunistic world: when the last encore is done, they turn the stage into a garage-sale for anyone wanting a squeeze-box or a cimbalom. Very good price, but the lessons will take a lifetime.