It was the hushed a cappella sound of Brisbane choir The Australian Voices that opened the Omega Ensemble’s Eternal Requiems, with Samuel Barber’s setting of the Agnus Dei from the Latin Mass. Originally from Barber’s 1936 String Quartet, the repeated use of the string orchestra arrangement of this music (the ‘Adagio for Strings’) in moments of public mourning – from the death of US President John F Kennedy in 1963 to memorials for the 2016 Orlando nightclub shooting and the 2017 Manchester arena bombing – has cemented it as firmly in the canon of ceremonial music for the dead as any purpose-built Requiem. Barber himself (despite his anguish that it had eclipsed all his other work) leaned into the work’s ceremonial associations by using it to set the Agnus Dei in 1967.

Gordon Hamilton, David Greco, Timothy Reynolds, the Omega Ensemble and The Australian Voices. Photo © Omega Ensemble

In this performance, the setting became a luminous prelude to Gabriel Fauré’s Requiem, in which the forces of the Omega Ensemble and The Australian Voices combined under the baton of Gordon Hamilton. While Donald Runnicles conducted the Sydney Symphony Orchestra and Sydney Philharmonia Choirs in Fauré’s large-scale 1900 version of the Requiem two weeks ago, here the Omegas presented a more intimate account, using Fauré’s 1988 scoring for choir and an ensemble of strings – sans violin section – as well as organ, harp, timpani and a solo violinist. The early version includes five movements – the Offertory and Libera me baritone solo (composed in 1877 as a stand-alone work) would be added later – and he skipped the Dies Irae, aiming for something more peaceful than the likes of Verdi.

From the outset the choir’s sound was gently enveloping, evoking very much, as Fauré put it, a “happy deliverance, a longing for the happiness of the beyond, rather than a painful experience.” Véronique Serret’s violin lines shone in the Sanctus and final In Paradisum, while soprano Christina Mairs’ solo in the Pie Jesu (originally sung by a boy soprano) was touchingly clear-voiced against the sensitive accompaniment of Sally Whitwell’s chamber organ.

The Australian Voices performed unaccompanied again for Hamilton’s own composition, Dark Hour, an affecting setting of words from a speech made by Australian Prime Minister Billy Hughes at the Savoy Hotel in London in March 1917 – describing the deaths of the men in Australia’s 8th Light Horse regiment at Gallipoli – rendered here with beauty and exquisite clarity by the choir, before – joined by organ, harp and strings – they brought the first half of the concert to a sublime close with Fauré’s Cantique de Jean Racine, an early work seen as a precursor to the Requiem.

Hamilton demonstrated his deft command of choral forces (not to mention the skill of the choir he has led for the last 10 years) in Dark Hour, but in the concert’s second half he brought them to bear on the world premiere of a new work, Requiem Recomposed, which took as its jumping off point the material left by Mozart for his never completed Requiem. From the uneasily swaying opening in the basses and low strings, it was clear this was not ‘Mozart’s Requiem’, the work instead unfolding as a kind of musical game (Mozart certainly wasn’t above such things himself) or thought experiment in which Mozart’s ideas are treated with contemporary techniques and instruments, from bass clarinet (David Rowden) to melodica (Whitwell, juggling organ, piano and synthesizer). The musical ideas ranged from plainchant to filmic textures and instantly recognisable Mozart themes – such as the vigorous fugue of the Kyrie, rendered crisply by the choir. Rowden drove the Confutatis from the bass clarinet, joining with double bass to evoke a powerful organ drone beneath the singers in the Hostias. The Dies Irae exploded out of a miasma of string tremolos and inventive timpani effects. Whitwell’s melodica was almost bagpipe-like at times, church organ-like at others, then taking on a seedier character for a carnivalesque rendition of the famous Lacrymosa (of which Mozart only ever wrote eight bars). It’s a fascinating, freewheeling work that will repay a thorough knowledge of the Mozart, its history and the various other bits and pieces Hamilton draws on – but it can be enjoyed on any level.

This program might have been brimming over with ideas, but it was gripping nonetheless. The Omega Ensemble and The Australian Voices gave sterling performances throughout, and while there was a moment in the Barber when the sopranos sounded a little tight in the upper reaches, the choir’s clarity and blend was impressive, the singers balanced neatly with the instrumentalists. They outdid themselves in the penultimate number: Benjamin Britten’s Cantata Misericordium, composed for the centenary of the Red Cross in 1963 and setting the biblical parable of the Good Samaritan, packed an opera’s worth of intense drama into under 20 minutes of music, with David Greco bringing his warm, assured baritone and a powerful depth of emotion to the Traveller, alongside the penetrating, keener edge of Timothy Reynolds’ tenor as the Good Samaritan. With its anxious string counterpoint and biting precision from the chorus, this was perhaps the highlight of the evening, which came to a close with the sweetness of Mozart’s Ave Verum Corpus.