MUSIC / On the edge: Adrian Jack on the Gabrieli's Mendelssohn, Janacek and Brahms at the Wigmore

The Gabrieli String Quartet was founded 25 years ago and has a new first violinist, Konstantin Stoianov, who replaces John Georgiadis, though many people will remember Kenneth Sillito in the original line-up.

Stoianov, a former leader of the London Philharmonic, gets a ripe sound from his instrument, but although he was born in Bulgaria and trained in Belgium and Germany, he hasn't changed the group's style, to judge from their concert at the Wigmore Hall in London on Wednesday. Presumably, that's not what they would have wanted.

The group began with a Capriccio in B minor by Mendelssohn, whose urbane opening Andante is followed by a neat, vigorous fugal Allegro. It rather set the mood of the evening, which was of good, sound music-making, avoiding extremes of feeling. That's hardly what one expects in Janacek's Second Quartet, whose title, Intimate Letters, testifies to passions of reckless abandon. It is music that rips open the medium and exposes the players in vertiginous antics, and makes them yield original and colourful sonorities which, in their way, are as daring as those of Bartok's Fourth Quartet, written in the same year, 1928.

Janacek's idiosyncratic idiom is now common property, though technical command - and simply playing in tune - often seem to be a problem. The Gabrieli didn't make a bad job of it, even though they lacked some of the ideal resonance, and there were some cruelly placed pitches, such as the first violin's darting upward phrases at the end of the third movement. It was a solid, honest performance, though short on character and capped by a rather tame final dance. Brahms's A minor Quartet is also a work of strong feelings and has always attracted rather patronising remarks on account of its supposed lack of idiomatic quartet-writing. So much the worse for the idiom, if that's the case, for quite apart from being completely cogent and consistently inspired as a piece of music, it is also full of imaginative touches of instrumental colour.

In the first movement, the Gabrieli explored too little variety of dynamics, and the mood lacked tension. The mezza voce of the second idea was too easy-going, and yet on a technical level there was nothing to betray the unmannerly snares that Brahms is supposed, in his ignorance as a mere pianist, to have set.

The orchestration and balance of the instruments may not be quite so exquisitely judged as in his later Clarinet Quintet, but there is still plenty to relish, and these players did, after their gentlemanly fashion. So the second movement wasn't quite as lush and flowing, nor the contrasting passages, in which Brahms bristles with passionate indignation, so alarming as they might have been. Nor was the third movement so crisply poised as to make us catch our breath. But Stoianov pitched into the finale like a champion, dead in tune. Even with their Bulgarian-born leader, the Gabrieli won't turn into a band of passionate Slavs, but they're in good shape.