Razumovsky Ensemble, Wigmore Hall, London <!-- none onestar twostar threestar fourstar fivestar -->

Founded in 1998 by the Ukraine-born, London-based cellist Oleg Kogan, the Razumovsky Ensemble is a flexible outfit drawing its line-up from a pool of leading orchestral players and specialising in larger chamber works. In this well-attended concert, the flexibility extended to a different first violinist for each of the three works.

The LSO's leader, Gordon Nikolitch, headed the line-up in Mozart's great String Quintet in G minor, K516, instantly reigniting the Razumovsky's characteristic style. This was vibrant, impetuous playing of huge dynamic range and projecting the work's recurrent pathos for all it was worth. Occasionally intonation suffered under the pressure, and one has heard more measured accounts of the muted slow movement, but there was no withstanding the intensity and sweep of it all.

Then, a sorbet: the Quartet for Bassoon and Strings Op 73 No 1 by the French composer François Devienne (1759-1803), who wrote some 300 instrumental works, and died "probably of overwork" as the notes told us - as, indeed, might any bassoonist less virtuoso and vivacious than Julie Price on this occasion, so incessant and florid is the solo part. Still, its three movements unfolded their 18th-century clichés with a pleasing lightness of touch.

But the focus of the concert was Brahms's too-little programmed String Sextet in B flat Op18, led by the sweet-toned Henning Kraggerud, but still dominated by Nikolitch, now as assertive first viola, and the sonorous Kogan as first cellist. This is the young Brahms at his most generous and inventive, the outer movements rolling forth on melodies of huge span, the dark slow movement variations accumulating a massive swing.

It is a work to be seen as well as heard, too, so graphic is the permutation of instrumental sub-groupings, so choreographic the counterpoint of gestures and bowing. And here the commitment of these players, body and soul, certainly told. Again, the emphasis was on energy and fullness, the ensemble throbbing with vibrato. But there was affection and charm, too: this deserved, for once, to be called heart-warming.