The Concord Sonata is one of the pinnacles of 20th-century music - a forbidding gauntlet thrown down by Charles Ives to the composers who came after him. This is Ives's masterpiece, nothing in his output better exemplifies his constant quest for the transcendental, his pursuit of an art in which expressive power triumphs over musical correctness. It's the only work in the piano repertory that can be compared with Mahler's orchestral efforts to contain the world in a symphony, and the world Ives evokes - a blameless New England community in the mid-19th century, in which the concerns of literature, philosophy and a love of nature were held in perfect balance - is conveyed through music that, more than 80 years after it was written, still seems astonishingly radical.
Despite its status, the challenges of Ives's piano writing and the density of the ideas make live performances rare. I met several knowledgeable people at Pierre-Laurent Aimard's recital who had not heard the work in concert. Now they have, they don't need to hear it again, for it is impossible to imagine the work better played. If Aimard's disc of the Concord Sonata, released last month, was extraordinary enough, in recital it was even more powerful. There was his masterful control of textures in the outer movements, Emerson and Thoreau; the cataclysmic climax visited upon the Hawthorne scherzo and the searching intensity brought to The Alcotts, the sonata's slow movement and emotional core where the Beethovenian spirit that hovers over the whole work is most fully evoked - everything fused into a unity by unswerving belief in the music's raw power.
Everything about the performance made the first half of Aimard's recital incidental, but for the record he had given a fleet, protean account of Beethoven's sonata Op 31 No 3, and an equally accomplished one of Thomas Adès's elegantly gleaming but ultimately vacuous Traced Overhead. In a week's time, though, no one will remember anything about it or the Beethoven, just the volcanic intensity of the Ives.
· Aldeburgh festival continues until June 27. Box office: 01728 687110.