Gustav Mahler, Jugendorchester, Barbican, London

When your name is the Gustav Mahler Jugendorchester, audiences come to expect Mahler on the menu. And when your conductor - as it was on this occasion - is Franz Welser-Möst, the spitting image of a young Mahler, the effect is positively spooky.

The cream of Europe's under-26-year-olds have been coming together now since 1986, when Claudio Abbado (who is still their musical director) put them on the map. But amazement at their extraordinary quality, their passion and their maturity, does not lessen.

An interesting selection of eight Mahler songs found the Royal Opera's current Papageno, Simon Keenlyside, bird-watching rather than bird-catching. Keenlyside - a wonderfully natural stage animal - is a most uncomfortable concert performer, and whilst we might initially have bought him as ideal casting for one of Mahler's typically wayfaring lads - his hand in his pocket, his shambling physical demeanour suggestive of shyness and unworldliness - the constant fidgeting, during and between songs, became distracting.

Nor did Keenlyside seem especially comfortable vocally. There were, of course, the rapt ascents into his lovely head voice as if scenting the fragrances of nature around him, but though, as ever, the German texts were clear and well-enunciated, the characterisation was rather uneventful, casual, nervy and short-winded. While Keenlyside did find an appropriately heroic vocal stance for the Rückert song "Um Mitternacht", the vulnerability and laudable restraint he brought to the heartbreaking "Ich bin der Welt abhanden gekommen" was marred by an inexcusable breath in the most beautiful phrase of all.

It didn't help that the orchestra - for all the delicacy of the playing, was at full strength. Fragile pianissimi just aren't possible in these numbers. This is precisely what made Strauss's Alpine Symphony such an earful.

With 100 or so fit young climbers deployed, the visceral thrills were there for the taking, the first trumpet fearlessly leading the expedition onwards and upwards. Dawn broke in a wash of ecstatic string sound. There were shimmering waterfalls, a bevy of rampant hunting horns, and the mother of all blizzards (with wind machine and thunder sheets). But I was puzzled that, having made the summit in such style, Franz Welser-Möst should have been in such a hurry to come down. The big horn theme that Strauss borrowed from the Max Bruch Violin Concerto was given short shrift indeed.