By way of complement to the orchestral concerts given in the Mariinsky Masterworks series at Symphony Hall, the final night saw the Mariinsky Chorus take centre stage. Here, the magnificent force and vibrancy of this 46-voice ensemble could be appreciated in its own right, richly resonant, and evoking not only the wealth of the St Petersburg performing tradition, but the vast heritage of Russian Orthodox music, too.

The main attraction was Rachmanov's Vespers, where the voices - unaccompanied, as the Orthodox Church demands - combine liturgical elements with melodies of folk-like simplicity and darkly dense harmony. In some ways, this work was an act of homage on Rachmanov's part but, in reaching deep into the Russian soul, it also represented a need to define an essential element of his own creative identity. In the light of his impending exile from Mother Russia, its emotional significance is considerable. The discipline of the Chorus and the tight control exercised by their conductor, Andrei Petrenko, was paramount, but it was in the characteristic colours of the different sections - the unselfconscious vibrato of the sopranos, the ample contraltos, fearless tenors and, most of all, the colossal treacly basses - that waves of emotion welled up, then stilled. And it was not the massive volume of sound that sent shivers down the spine, but the pianissimo as it disappeared into air.

The Orthodox Easter Music sequence was less compelling, but afforded a rare historical perspective, reflecting both Imperial and post-Soviet Russia and the re-embracing of the Orthodox faith. The Varlaam prayer O Radiant Light, echoing a text from the vespers, commemorated the restoration of the Valamo monastery in Finland, once a Russian military base, while Pavel Chesnokov's Pascal hymn celebrated the anthemic status his music achieved for Orthodox Russians in the early 1990s. Each was moving testimony.