Ensemble Modern/Asbury, Barbican, London

The Ensemble Modern's sold-out Steve Reich concert culminated in the British premiere of You Are (Variations), a work for six voices and 28 players.

The Ensemble Modern's sold-out Steve Reich concert culminated in the British premiere of You Are (Variations), a work for six voices and 28 players. The "You Are" of this substantial composition - nearly half an hour long - refers to the "aspects of existence" explored in the four movements' epigrammatic texts. The first of them, from Hasidic mysticism, reads: "You are wherever your thoughts are." Variation form provides the basis of each movement's structure.

You Are (Variations) opens on almost too-familiar ground. The scrunchy, repetitive chatter of pianos accompanying the interlocking patterns of marimbas and vibraphones, and those swelling and fading female voices and clarinets: we've surely heard all this before.

Yet as it progresses, Reich's new work soon transcends any feelings of retread. The treatment of four pianos - four real, grand pianos - is one indicator of fresh thinking. Chatter there is, certainly, but they also take on a much darker role. More chordal piano writing brings a new nervous energy; there's also some splendidly searing writing for the 13-strong string group.

Despite what's been said elsewhere, I found that at least some of the subtle chromatic harmonies and impressive propulsion of You Are have an expressively ominous aspect. Exploring the possible meanings behind the opening movement's text caused the composer to vary and deepen an already rich harmonic groundplan: for example, by stacking conflicting harmonies on top of one another.

All the other movements are shorter, but their terse texts are no less redolent with meaning, whether set in English ("Explanations come to an end somewhere", from Wittgenstein) or Hebrew ("I place the Eternal before me" and, quintessentially for Reich, "Say little and do much"). And the music is in every case rich and challengingly complex too, constantly coming up with fresh angles to the composer's trademark rhythmic energy and contrapuntal complexity.

Under a relaxed Stefan Asbury, Synergy Vocals and Ensemble Modern combined power and subtlety with a marvellous clarity. Perhaps they'll find more insouciant ways of unpacking the jerky dance rhythms of the finale, but otherwise these two groups have already pretty much cracked this new piece.

They also gave an incisive yet beautifully blended account of Tehillim, while a reduced Ensemble Modern alone produced the best performance of Eight Lines I have ever heard. In both works, these musicians showed they knew exactly how far to mould and nudge the dynamics beyond what it says in the score without ever falling into over-expressiveness. It's also excellent news that the Barbican will be mounting a 70th-birthday festival for Reich, including a revival of The Cave, in the autumn of 2006.