DANCE : Lorca, where are you now?

WHAT British audiences know of live flamenco is largely due to the efforts of one man, Francisco Sanchez. It was his idea 10 years ago to pick off the top performers from Spain's premier annual flamenco festival, and send them round the world each year as Cumbre Flamenca. "Cumbre" - the summit, the best of Andalusian culture. And few disputed it.

The staging was simplicity itself - a couple of singers and guitarists, some hand-clappers to keep the rhythm on track, standing in a gaggle on stage just as they might in some taberna back in Granada. And dancers, what dancers: pouting girls, square-bosomed matrons, snake-hipped young men and crepe-faced veterans, all fiercely individual and grandly self- absorbed. Time and again Sanchez's troupe made audiences believe they were being warmed by real gypsy fire.

Now Sanchez is back with a new company, Corazon Flamenco, and a one-act flamenco drama which had its world premiere at Sadler's Wells on Tuesday. Ay-ay-ay, as the jondo singer would wail, ay-ay-ay! From the vastly over-amplified strumming of the opening, through the B-movie central romance, to the histrionic denouement, the work is a travesty of Sanchez's previous form and, in the name of progress, perversely trashes much of what makes traditional flamenco unique.

Only a museum curator would argue that the art should not move on. But this? The audience tittered when the cuckolded husband brandished his long rifle, and the lover answered with a little gun. Pop, pop. The fallen woman was lugged by her lover into a large tub. We laughed again at the effort. For shame. Sanchez interpolates into the traditional dance forms a series of melodramatic sequences that don't broaden flamenco so much as undermine it. Traditionally, proud male and self-aware female rarely touch. The sexual charge is potent and thrilling. Here the mauling lovers snog on stage, disrobe and invite the voyeurism of a Spanish TV soap. Lorca, where are you now?

Banishing the musicians behind screens for half the show was a very bad idea. Not only does the audience want to see them, but the dancers need to. The live, physical connectedness of music and movement, both being improvised over a rhythmic and harmonic frame, is surely one of the great absolutes of the art. More than once the rhythms of heels lost touch with the rhythms of clapped palms, and no wonder.

The company's musicians are very fine, but their quality is all but obliterated by crass amplification that brings everything up to one dynamic level and pours it through speakers on the far side of the stage. They might as well be miming to a tape. And when the singers screw up their faces and build to a melisma of wailing, we wince with our own pain. It's far too loud. The marvellous grain of the voices is gone, expressive dynamics set at nought. So too is the zapateado - the music of the dancers' footwork - which joins a melee of noise coming from nowhere in particular. The pitos - the delicate clicking of fingers - does not even register on the scale.

Is this the result of a huge inferiority complex, or a sound technician wagging the dog? Why can't this sophisticated art be allowed to speak with its own voice? Sadler's Wells has all the acoustic projection these great performers need. Gross amplification has the opposite effect of what was surely intend- ed: rather than bringing flamenco up close, it's depersonalised, alienating.

But the show recovers. A too-short second half leaves flamenco to its own magnificent devices (apart from the love affair with mikes) and introduces some major mature talents. Susi, the diminutive singer, sits simply, centre stage with a guitarist, and beguiles in a sweet, low rasp. Later, she ups and whips across the space in a fury of drumming heels and fussing skirts, a match for any of the young flibbertigibbets around her.

The star dancer, Manuela Carrasco, is statuesque in figure, monumental in style (they call her "The Goddess" in Spain). Tailored from neck to ankle in stiff white satin, she broods over some desultory footwork, appears to lose interest, then erupts in a snarl of lashing arms and legs and fringes, seizing her heavy train as if it were a bundle of wet washing and kicking it about sullenly with her knees. She is terrifying, electrifying. She and Susi together could fire a small power station for a week. Give them the whole show, Senor Sanchez, and take the biggest risk of your career: forget the play-acting and pull out all the plugs.

'Corazon Flamenco': Sadler's Wells, EC1 (0171 713 6000), to 10 Feb.