Leif Ove Andsnes founded the Risør Festival only nine years ago, but it's already an important part of the European calendar. Risør is unique because it's a musicians' festival. Everyone gets together in this small Norwegian town, no matter how famous they are. This atmosphere's great for chamber music, so the Wigmore Hall is an ideal second home for Risør in London.

Because Risør is a festival for musicians, it's adventurous. Eclectic repertoire, and an open-minded approach, typified by this fourth concert in the Wigmore Hall Risør series. For example, Stravinsky's Rite of Spring. Not the ballet, but a version for keyboard here heard on two pianos with Andsnes and Marc-André Hamelin. The austerity concentrates the mind, focussing on the basic structure of the music. Here the Rite is revealed in primal essence. One piano outlines the famous opening theme, the other adding darker, more menacing undertones. The jagged outlines aren't smoothed over, the lyrical inventions fly freely. Andsnes and Hamelin stalk each other, acutely observing, as if caught up in stylized ritual. No dancer, no ensemble, but two pianists in duel. Emphatic, stomping are ostinato pounded out by fingers instead of feet (and large orchestra). Instead of sheer volume, one notices the angularity in the writing, still shockingly original after 90 years.

No wonder Andsnes and Martin Fröst prefaced the Rite of Spring with early Alban Berg, 4 Pieces for clarinet and piano op (1913). These brief aphorisms don't allow Fröst and Andsnes much room for virtuosic display. At the lunchtime concert on earlier on this day, Fröst would have shown his range in Mozart's Clarinet Quintet in A, K581. In Berg, he and Andsnes impressed by their austere restraint.

Again, adventure in Ralf Wallin's Under City Skin for viola, strings and surround sound, first heard at Risør in 2009. The composer describes as a way of hearing things on different levels, seeing archetypal myth beneath the grim reality of a cityscape. Hence the "footsteps", sounds that move forwards and backwards, from different angles. It's deliberately disorienting, especially at the Wigmore Hall where we're conditioned to hearing from only one dimension. The result is that there's a constant battle between what we recognize as conventional music and this strange disembodied counterpoint. It's a good way of shaking up auto pilot listening. Risør does counterpoint in the widest meaning of the term. Wallin was followed by a brief Bach piece for viola. We may not be listening to Wallin in 300 years time, but for a moment the Risør magic reminds us that basic principles don't change, just context.

From the minimalism of Berg to the relative maximalism - for the Wigmore Hall - of Arthur Honneger's Symphony no 2 for string orchestra and trumpet. Austere, spartan restraint, but also the clarity you get on a chill morning, when there's little background distraction. Yet Honneger contrasts the elegance with strange, wailing themes, "smeared" notes which counterbalance the formality. Is it an incantation, or a cry of anguish? Hearing Honneger after Stravinsky focuses the mind on the idea of ritual as means of placating fate and cosmic dangers. Significantly, Honneger was writing in 1940-1. The references to Bach confirm the idea of faith (of any type) in times of tribulation. Counterpoint again ! In the third and last movement, Vivace non troppo - presto, a trumpet materializes in an archway, usually closed off, above the platform. Trumpets symbolize angels, of course, but musically this is powerfully effective. The strings aren't alone. Their chorale-like theme is reinforced for the deeper and more strident tones of the trumpet, playing in parallel. Excellent performance by the Risør Festival Strings, conducted by Per Kristian Skalstad.