Mixed Choral Chorus from London, UK, England.

For over half a century, this London-based chamber orchestra has repeatedly proved that it can achieve, without a conductor, the precision and level of expression generally attributed to the presence of the guy with the baton. Furthermore, within the challenging demands of Mozart's orchestral music, with its built-in demands for a somewhat homogenous approach, the ensemble achieved an engaging variety of timbres and moods.

Violinist Kenneth Silito, sitting in the position of concertmaster, had been technically the leader of the conductorless ensemble before intermission. Pianist Jonathan Biss took on that role as piano soloist for the final work, the Piano Concerto No. 9 in E-flat, which stands out among the composer's thirty-odd concertos for its unique structural gestures and frequent whimsicality. Biss produced a deliberately bright, transparent sound to merge with the orchestra, at the same time applying a sweeping, almost romantic sensibility. The result was unique and striking, particularly in the pathos-driven middle movement. Biss and the orchestra pushed a bit further ahead in the Mozart chronology for the encore, the final movement of the Concerto in A, K. 440. Here, they achieved the remarkable effect, based largely on the harmonic instability of the piece, of music in which the actual sound and cheerful mood are just the facade of a more chaotic, tumultuous core.