Undervalued works by Tchaikovsky and Stravinsky make ideal musical bedfellows in Aix

The ear was ravished throughout this double bill from the Aix Festival, a hook-line-and-sinker import from Madrid first seen at the Teatro Real in 2012. It was a reminder, if one were needed, of the unique colours that Russian music can display when it's sung with idiomatic splendour. A special gong, then, to the Choeur de l'Opéra de Lyon for holding its own in Tchaikovsky's Iolanta alongside a cast of predominantly native singers.

Cool young conductor Teodor Currentzis has a precocious pedigree that belies his skinny jeans and street cred, and on this showing it's perfectly clear why that is. The Greek-born music director of Perm Opera draws fabulous playing from the Lyon orchestra and featherbeds his singers in the most stylish fashion. From the all-wind overture and onstage string quartet to the sweeping mournfulness of Tchaikovsky's tuttis – so startlingly redolent of the near-contemporaneous Pathétique Symphony – Iolanta is an aural feast.

Despite its sumptuous score, this operatic story of a blind girl cured by hocus-pocus has drifted out of the mainstream. That's probably understandable since Henrik Hertz's source play, as shaped into a libretto by the composer's brother Modest, is weak stuff that's unconvincing even as a fairy tale. Dramatic tension between the characters is all but non-existent: nothing, for instance, is made of the potential for rivalry between the heroine's two suitors. “You want her?” asks Maxim Aniskin's sonorously sung Robert (though not in so many words). “That's handy, because I'd rather marry Mathilde.” And while Willard White's apparent quack doctor turns out to have real healing hands, the inconvenience of rustling up a secret for his sight-restoring powers, be they medical or magical, is sidestepped.

If we overlook the fatuous narrative, though, we can celebrate an enchanting score that earns a proud place in the composer's late oeuvre. It's easy to see why Tchaikovsky, a romantic homosexual thwarted in love who would soon put an end to his own life, should warm to the tale of an outsider who overcomes her otherness and finds inner peace. The fantasy of Iolanta's happiness was his own wish-fulfilment.

With stirring performances by Ekaterina Scherbachenko as Iolanta and Arnold Rutkowski as the hero Vaudémont who finds her and falls instantly in love, not to mention a show-stopping prayer aria from Dmitry Ulianov as her father, King René, this iridescent opera hardly needs Peter Sellars there to direct any borrowed light into it. Yet in fact, some overly busy backdrops aside, Iolanta finds the old iconoclast at his most pared-back. He's a latter-day Peter Brook in his empty-space approach to an opera that could easily accommodate a spectacle as opulent as The Nutcracker, the ballet with which it was originally coupled. Sellars' only major misjudgement is to open up the bare stage and wings so fully that the singers' bloom and volume recede the moment they step back from the downstage edge.

George Tsypin's odd little set – four doorways topped with oversized natural history artefacts – does double service for both Iolanta and Perséphone. Stravinsky's melodrama to a poem by André Gide has not been greatly loved since its composition in 1934, probably because it's hard to pin down and demands large forces. Yet it contains some of the Russian émigré's most perfumed music. It takes a few hearings to reveal its beauties, and admittedly some sections remain arid no matter how often you listen, yet much of the choral writing (this time in French) is wonderfully tender. The lilting “Ivresse matinale” is a musical sugared almond, the children's chorus “Nous apportons nos offrandes” a charming floral garland.

Essentially the work is a cantata, although Stravinsky himself called it an “accompanied narration”, and it is often presented (as here) in a choreographed staging. The tale of Persephone, daughter of Demeter and Zeus, is a Greek nature myth in which the young goddess brings flowers to the Underworld and initiates seasonal change above. Sadly, though, Sellars seems less inspired by it than he was by Iolanta and he inflicts a risible overload of trademark hand-jives on the game Lyon choristers, who do their best to oblige.

Dancers from the Amrita Performing Arts add exotic visual allure, and the final section is given a lift by the girls of the Maîtrise de L'Opéra de Lyon, sounding excellent in music that Stravinsky originally intended for boys' voices. But the tenor Paul Groves is now a gruffer soloist than suits the clean-limbed score, while Dominique Blanc's narration is filtered through an unwelcome microphone into which she caresses half-whispered lines in the lobe-licking tones of a French radio ad.