Joshua Bell and friends in Czech chamber music at Wigmore Hall

'All-star' recitals are funny old things. Bringing together some of the leading lights of the present musical world to make music together is an idea that seems pretty well irreproachable at first; unfortunately, they can often go to show that the very best chamber groups are rather more than just the sum of illustrious parts. I'm probably being slightly harsh about 'Joshua Bell and friends' – the American superstar apparently counts pianist Jeremy Denk, cellist Steven Isserlis , and violist Lawrence Power amongst them – but only because their first Wigmore Hall concert was a case in point. Bringing to a packed house a concert of gorgeous Czech chamber music, the group's ravishing account of Dvořák 's Piano Quartet in E flat was let down by a weak first half plagued with intonational and technical slips, as well as a wholly unwelcome sense of competition.

Josef Suk's Piano Quartet in A minor is a miraculous work, written when Suk was just 17 years old and brimming with youthful confidence. The group's slightly devil-may-care approach to attack paid off handsomely in such vigorous music, but poor Denk was left covered by the force of the strings, something that would cause concern throughout the evening. Power's solos were exquisitely expressive, and the quartet was clearly enjoying itself, but enthusiasm could not cover up some really rather unpleasant slips of intonation from Joshua Bell. The Berlin Philharmonic's old principal horn Gerd Seifert was notorious for playing just slightly sharp in order to hear himself and ride above the texture, something Bell was seemingly attempting too. Unfortunately, sharp is still sharp, and the octave melodies were less than beautiful.

This quartet gave the impression of a group of individual players who have come together ad hoc rather than a well-honed chamber ensemble who understand each others' playing and agree on an ideal sound. It wasn't surprising, therefore, that Bell was much more impressive in Janáček's Violin Sonata, a dark, ruminating piece with little consolation to offer. It's not a particularly beautiful sound that Bell makes, but his confidence in articulation and gift for well-placed aphorism were both clearly in evidence, particularly in the tormented utterances of the first and last movements. We never feel so very far away from the delicacy of On an Overgrown Path, and Bell captured the mood well, though a tendency to start vibrato rather late often gave the impression of rather unpleasant swells, a characteristic that appeared a few times in the wider group too.

Steven Isserlis took to the stage for Martinů's Cello Sonata no. 2. It's not a piece that really measures up to the others in the programme in terms of quality, with a rather anodyne piano introduction not really allowing Jeremy Denk much in terms of expressive possibility. From here it develops into streams of intricate, quirky counterpoint, and though Isserlis' nobility of tone was very pleasing in the grave slow movement, much of the sonata was rather bogged down in the notes. The British cellist plays with astonishing energy and commitment at all times, and clearly loves this music, with a long note in the programme expounding its virtues. Although there are problems with the music itself, this commitment made itself quite clear with an absolutely furious last movement cadenza leading to a bright, positive finish.

What a change for the Dvořák in the second half! Gone was the unsettling intonation, gone that sense of competition. Lovely solos again from Lawrence Power and a strong, commanding turn from Joshua Bell, with Jeremy Denk finally getting some music to get his teeth into, with gorgeous octave melodies and head-turning pianissimos. I had a real sense that the ensemble was being led by Denk, his sonic control pushing the group to the extremes of virtuosity and shade. This was particularly clear in the lyrical but highly intricate, jeu perlé piano part for the waltzing scherzo. Unfortunately, in creating a new, dramatic mood for the trio, the ensemble went too far, excessive weight masking that dancing playfulness that must remain under the surface.

I think this latter observation more or less summarises my feelings about the Dvořák as a whole. Although technically and musically it was much more settled, an excess of force tended to cover up the fundamental grace of the Bohemian's pastoral imaginings. Group chords began their vibrato very late, giving us just bow weight at the beginning – the result was a rather overwrought, tense sound, not well-suited to this open, free-ranging musical landscape. All very passionate, a commendable quality to be sure, but not always beautiful, something essential for Dvořák's music.

I was slightly disappointed by this evening on the whole; as is the danger with the 'all-star' date, it tended to lack those tiny finesses, those infinitesimal differences which mark out the great ensemble from the merely very good.