If you were a fiddle player, and Anne-Sophie Mutter, Maxim Vengerov and Yehudi Menuhin had all turned up at your gigs, you'd have to be doing something right. Just like Roby Lakatos, the classically trained but gypsy-inspired Hungarian violinist who is now at Ronnie Scott's with his quartet.

It's not as wild and deliriously undignified as the Romanian Taraf de Haidouks ensemble, which last brought gypsy music to Ronnie Scott's, and Lakatos's playing has more angelic purity than the rougher, more approximately pitched work of the Romanians. But the violinist proved on his opening night that close observance of the rituals of traditional Danube-cafe music has not blunted his urge to improvise. And though there was plenty of swoony, romantic rhapsodising (maybe a little too much of it for the audience, which looked a little restless in these episodes), he has an ear open to a more modern world than 19th-century central Europe, even if he hasn't quite made it all the way to the 21st.

The leader's breath-taking technique really came into its own on the up-tempo Hungarian folk-dance music, which was full of crash stops, sly build-ups and headlong nosedives like a journey on fairground switchback. Fast bowing released notes that came at you like hailstorms, mixed in with sudden slashing discords and beautifully constructed long runs.

Lakatos's technical mastery was matched by cimbalom player and guitarist Ernest Bango, whose name seemed particularly apt when he handled the former instrument. He displayed a clattering virtuosity as he did the work of vibes, keyboards and drums at once. But the intriguing aspect of the ensemble is its closet jazz inclinations. Pianist Kalman Cseki played some crisp, boppish interludes, Bango expertly caught the Django Reinhardt Hot Club sound on guitar for Lakatos to wheel and dive over, and the phrasing of this music's deepest traditions was subtly reshaped in Lakatos's hands. It won't be enough of a jazz band for some, but it certainly means business.

Lakatos is at Ronnie Scott's, London W1 (020-7439 0747), till Saturday.