Asked by the Zurich period orchestra La Scintilla to choose a work for a charity performance, Nikolaus Harnoncourt gave a typically left-field response: Haydn’s little-known Italian oratorio Il ritorno di Tobia, hampered by an inept, sub-Metastasian libretto that botches almost every opportunity for drama in the story of Tobias from the Apocrypha. With its succession of vast bravura arias, framed in the original version by just three choral numbers, the oratorio was already deemed old-fashioned in Haydn’s lifetime. Concert performances will always remain scarce. But as the studio recordings by Dorati (Decca, 10/94 – nla) and, especially, Christoph Spering have shown, if you can adjust to the ultra-leisurely time-scale, there is a wealth of vivid, richly worked music in what is essentially a Neapolitan-style sacred opera.

Both on its 1775 premiere and its 1784 revival (for which Haydn pruned several arias and added two magnificent choruses), the receipts from Tobia went to the Viennese society supporting of musicians’ widows and orphans. Proceeds from this 2013 Salzburg performance were given, aptly, to a charity supporting youth projects in war-ravaged Bosnia. Harnoncourt obviously believes fervently in the work, and with one exception he fields a good cast. Yet the result is at best a mixed success. For one thing the acoustic of the Felsenreitschule is paradoxically both cavernous and, as caught here, airless. Balances are sometimes awry (the excellent Arnold Schoenberg Choir lacks impact), with an over-prominent jangly harpsichord. And while La Scintilla play with a will, their tuning and ensemble are, perhaps inevitably, rougher than on either of the rival recordings. Violins are underpowered, oboes and cors anglais (whose pungent timbre colours many numbers) faintly wheezy. In the luxuriously scored aria ‘Non parmi essere’ – a sinfonia concertante for soprano and wind – the players of Spering’s Capella Augustina are in a different league for polish and poetry.

True to form, Harnoncourt’s direction favours brusqueness and punchy rhetoric over elegance. The searing ‘storm’ chorus, ‘Svanisce in un momento’, is frenetically driven, the players barely clinging on. Conversely, recitatives and lyrical arias can plod, with Haydn’s repeated bass lines chugging rather than gently pulsing. As on Spering’s recording, Ann Hallenberg is perfectly cast as Tobit’s wife Anna. Making more of her words than anyone else in the cast, she brings a terrific energy to her opening coloratura aria (and never mind the odd wild moment above the stave), and uses her sulphurous chest register to baleful effect in her ‘nightmare’ aria in Part 2.

Sopranos Valentina Farcas, as Tobias’s wife Sara, and Sen Guo, as the disguised Archangel Raphael, both display bright, confident tone and rise impressively to Haydn’s virtuoso demands. Farcas also sings the ravishing ‘Non parmi essere’ – described by Harnoncourt as ‘the oratorio’s high point’ – with much delicacy of feeling. Of the men, I enjoyed Mauro Peter’s youthful tones and graceful phrasing as Tobias, though his low notes lack fibre in the bravura aria ‘Quel felice nocchier’. In the predominantly reflective role of the blind Tobit, Ruben Drole sings coarsely, like a misplaced basso buffo. Legato is evidently an alien concept to him. Harnconcourt completists will doubtless want this; and the occasion was evidently a moving one. But for all the merits of this Salzburg performance, Spering’s recording – more fluently paced, better played and on the whole even better sung – remains my recommendation for anyone wanting to explore a fascinating, sometimes thrilling Haydn rarity.