It can't be often that a poet declares that the selection and setting of his words to music has turned them into better poetry. But then not many poets get their work set by a composer of the stature of Dmitri Shostakovich, when, in 1961, he set five poems from Yevgeny Yevtuschenko's collection "Babi Yar", named after the ravine in Kiev where the Nazis had machine-gunned thirty thousand Jews twenty years earlier.

The resulting work is more of a cantata or song cycle than its "thirteenth symphony" label might imply. Be that as it may, it's hard to argue with Yevtuschenko's assessment. The five poems are on widely diverse subjects (ranging from reflections on the Babi Yar story to the career of Galileo, passing by Humour, Fear and the silent heroism of ordinary women) but they share the common driving force of an intense, passionate statement of the difference between good and evil. In every one, Shostakovich's music finds means to illustrate and amplify; it's music of infinite variety and invention which can shock you at improbable moments. In the second movement, the idea of humour as the force that tyranny cannot extinguish is played out with huge energy - and, yes, humour. The third movement starts as a prosaic description of the patience endured by thrifty Russian housewives but switches to a denunciation of the corrupt: the words "It is shameful to short-change them" hit you like a thunderbolt. And you continually feel that the music is telling you more than the words: when the fourth poem opens with the statement that "Fears are dying out in Russia", the music tells a different story.

Sergei Aleksashkin has the sort of voice that makes you sit up and listen: dark, full, stentorian. When he sings that he feels like the Wandering Jew in ancient Egypt, you feel the centuries in his voice; when he sings "that is why I am a true Russian", you cannot avoid swelling with pride in sympathy. It's no longer the most melodious of voices, with little in the way of lilt to follow Shostakovich's elegant phrasing, and it did seem to me that Aleksashkin struggled to reach notes at the top of his register. But still, particularly for quintessentially Russian material, it remains a voice to be reckoned with.

Aleksashkin blended well with fine singing from the male choir (Philharmonia Voices) and with equally fine playing from the Philharmonia, conducted by the small figure of Vladimir Ashkenazy. String timbre was superb, brass and percussion interventions potent enough to knock you off your feet. Watching Ashkenazy conduct was interesting: I don't think I've ever seen orchestral players more focused on their scores (and therefore not watching the conductor) yet the performance was perfectly together without a hint of raggedness.

Ashkenazy is quite elderly now, so before the interval, it was poignant to see him helping the much younger pianist onto and off the stage for the performance of Prokofiev's third piano concerto. This was essential because that pianist, Nobuyuki Tsujii, has been blind since birth. The Prokofiev work is percussive and highly complex rhythmically, and Tsujii played it with great precision - a remarkable achievement. From a slightly downbeat start, he seemed to grow in confidence as the work progressed; by the end of the third movement, he was bringing out Prokofiev's full ebullience. It's a mercurial concerto with many flights of fancy, and the orchestra were on fine form, but unfortunately, the balance wasn't always right. Tsujii isn't the loudest of pianists and while this was didn't matter at all in his solo moments, he was rather drowned out on the passages where pianist and orchestral tutti played together.

The Prokofiev concerto is a fun divertissement of a piece and has every bit of the variety and invention of the Shostakovich. But it lacks the symphony's seriousness and unifying sense of purpose: I question the wisdom of juxtaposing the two in a single programme, however well performed. Leaving that aside, however, I will remember this performance of the Babi Yar Symphony for a long time, because it is such an uplifting work. The music takes Yevtuschenko's strong sense of morality, expands it and hits you with clarity and directness; Aleksashkin and Ashkenazy's interpretation brought this out to the full.