Gould Piano Trio, St Lawrence Jewry, London<br/> Brodsky Quartet, St Michael Cornhill, London<br/> Zaide, Barbican Hall, London

The most interesting musical events in this year's Japanese-themed City of London Festival have been the early evening non-Japanese chamber recitals. Bracketed under the title "Postcards from...", each week's series has focused on a particular city: Vienna, Paris, and St Petersburg. Such is the concentration of festival venues in the Square Mile that one can stroll to the next concert without breaking into a sweat, as was my intention on Tuesday. So devastating was the Gould Piano Trio's performance of Shostakovich's Trio No 2 at St Lawrence Jewry, however, that I changed my plans. After Shostakovich, who needs Takemitsu?

Written in 1944, the Trio was inspired by Nazi atrocities at Treblinka. Shostakovich, who had been evacuated from Leningrad, was haunted by reports of Jews being forced to dance at gun-point on mass graves. Hence the brutal passacaglia for piano (Benjamin Frith), hence the shell-shocked wail of harmonics, hence the traumatised dreydlekh, hence the world-upside-down insanity of a sher for cello (Alice Neary) and violin (Lucy Gould), stripped of all joy and hope and humour. Master musicians in Arensky's opulent Trio in D minor - their octaves impeccably tuned, their articulation graceful, their phrasing intelligent, their sound delicious - the Gould Piano Trio here proved themselves to be master dramatists. Gould and Neary's blanched, then bloody tones, and Frith's near-orchestral control of dynamics made this an uncommonly powerful and disturbing experience. Like George Rodger, Robert Capa and Lee Miller, Shostakovich looked for art in the face of atrocity, and for that, however harrowing the result, we should be grateful.

Altogether less impressive was the Brodsky Quartet's postcard, which might have read "Wish we weren't here." Under pressure to leave St Michael Cornhill in time for their performance of Janacek's Intimate Letters at Wilton's Music Hall, they delivered a scrappy performance of the original 1920 version of Stravinsky's Concertino, a work that demands neatness. Shostakovich's Quartet No 11 was better prepared, though the intonation was again poor. When they play softly, as in the honeyed slow movement of Tchaikovsky's First Quartet, they blend well. At forte, their sound is ugly. I too would have liked to have been elsewhere.

Was Mozart an abolitionist? Peter Sellars thinks so, and prefaced his modern-dress, sweat-shop semi-staging of Zaide - plumped out with incidental music from the melodrama Thamos, König in Aegypten - at the Barbican last week with an impassioned speech to that effect. When added to statements from the representatives of Anti-Slavery International and The Poppy Project, this meant that the musicians of Concerto Köln were on stage for a full half-hour before they played a single note.

Never has the phrase "captive audience" had such resonance. Some were moved by the speeches. Some were audibly disgruntled. But regardless of Sellars's belief that he should speak out against injustice wherever possible, the performance suffered both from the delay - the later the hour, the poorer the concentration of the listeners - and from his concept. Zaide may be less chintzy in its musical depiction of "otherness" than Die Entführung aus dem Serail, less self-conciously exotic in its soundworld, but it is hardly a work of political invective. Mozart, who routinely imbued his heroes and villains with equal humanity, was apolitical to the bone. Furthermore, the stock character of the Noble Turk had been treading the boards in Europe for several centuries before Zaide.

It is understandable that this incomplete, occasionally lovely singspiel is best known for the heroine's limpid aria "Ruhe sanft", but its finest moments are the orchestral accompaniments to Soliman's vengeful soliloquy "Zaide entflohen and Gomatz's touching Unerforschliche Fügung". Under Louis Langree, Concerto Köln played these melodramas with astonishing dynamism, the acuity of their strings agreeably offset by rasping brass.

Though the instrumental interludes from Thamos left the cast stranded for long periods, their musical performance was excellent. Soprano Hyunah Yu (Zaide) has a startlingly pretty voice - think Kathleen Battle without the neurotic mannerisms - while tenors Norman Shankle (Gomatz) and Russell Thomas (Soliman) showed lyrical talents that made one wonder why they hadn't been heard in London before. The answer, alas, is obvious. Unconvinced as I am that Mozart was an abolitionist, or an -ist of any political persuasion, Sellars's most important act as a Mozartian director has been to cast African-American artists in a medium that is still, 227 years after Zaide was composed, almost exclusively white.

a.picard@independent.co.ukA