Emerson Quartet | Wigmore Hall/Barbican, London

How democratic is a string quartet? Its history might be expressed as the gradual evening-out of the technical load between the four players. In this sense, the suggestion is that no one "leads". The Emerson Quartet has taken one further step: there is an equal sharing of the violin parts between the two players. No danger that one player will shine and the other inhabit the shadows. But what seems to be sacrificed is character. When the two violinists of the Emerson swap places, by definition, they should be of equal weight. And in a sense they are, but sameness spells dullness. This sharing of "first chair" is a feature of the Emersons but not explained. In a domestic setting, the sharing of roles is welcome; on the concert stage, it is less so.

The Emersons began their Shostakovich string quartet cycle on Friday at the Wigmore Hall. Four more concerts follow, two at the Wigmore, two at the Barbican. The series has been sold out for weeks. It's a sales opportunity for their recently released complete Shostakovich quartets on Deutsche Grammophon. Some areas of the classical recording industry are on their knees; the Emersons and/or DG are taking a belated leaf out of the pop industry's arsenal and giving concerts specifically to sell discs - or perhaps it should be "albums"?

Like their recordings, the quartets in this series are presented chronologically. The problem is that Shostakovich was a bit slow in getting going, even though his first quartet was written as late as 1938. He had already written five symphonies and got into deep trouble with the authorities. Curious, then, that Shostakovich in this piece seems to revert to a kind of immaturity of style, as though he felt obliged to begin again, acknowledging that by definition any first string quartet must be immature. True, Shostakovich wrotes that in this quartet he visualised childhood scenes.

The Second Quartet, written six years later, is a different animal. The mood is dark, uneasy, restless, even if it starts breezily enough. Eugene Druker took pole position for this quartet and the first, but in the intense recitative of the Second Quartet's second movement, his brittle brilliance failed to move.

There can be no argument about the quartet's technical prowess, particularly in the matter of volume. What seems lacking is soul. Joseph Kalichstein, joining the Emersons for Shostakovich's Piano Quintet, a work written between the two quartets, provided some. A sensitive player, Kalichstein brought out the springiness in Shostakovich's Schubertian octaves. But the answer to the question "Who leads?" is clear: the viola. Time and again in this concert, the staggeringly beautiful playing of Lawrence Dutton, intense, subtle, passionate and warm, dominated proceedings. But perhaps he feels more secure. After all, he can't be swapped.