Prom 42: WNO / Sinaisky, Prom 43: BBC SO / Saraste, Royal Albert Hall, London *** / ***

Extraordinary refinements in scoring are common to both, but there is nothing in Iolanta to compare with Nutcracker's great transformations. As Sinaisky's orchestra demon-strated, the high drama of the great Pas de Deux between the Sugar-Plum Fairy and Prince Consort Orgeat has to be the most inspiring use of a simple descending scale in the whole of music.

Iolanta starts wonderfully, with a prelude vividly placing us at the centre of its blind heroine's enclosed world. A lachrymose cor anglais supported only by bassoons is darkly tentative, but gradually, as Iolanta's senses awaken, the fragrance of the wind writing and almost imperceptible arrival of the strings beautifully conveys her idyllic retreat. Nuccia Focile as Iolanta is that rare thing, an Italian soprano with an ear for Russian colour, and she was ably partnered by the British tenor Peter Hoare as Vaudemont.

The following night, Marc-André Dalbavie's new Piano Concerto began with a fusillade of double-octaves against slides of derision from trombones. Octaves were the stock-in-trade of the traditional romantic piano concerto. Times have changed. Now they fulfil a spacial function. Dalbavie calls it "spectralism", and it manifests itself as a time-and-space-stretching device wherein the sounds appear unconstrained by structural requirements. It's an illusion: the piece has three movements, a beginning and end. But what comes in between sounds open, pellucid and weirdly static.

Leif Ove Andsnes made much of its ruminative solos, personalising them, giving them reach like a spaced-out Ravel. The odd muted trumpet hinted at a jazz age long gone.