New Queen's Hall Orchestra Barbican, London
As George Bernard Shaw once said, disparagingly: "The law of traditional performance is 'Do what was done last time'." The remarkable New Queen's Hall Orchestral, however, dares to be different, bringing "period" instruments and performance practice to bear on early 20th-century music.

The effect can be revelatory, and certainly was in this splendid rendition of Mahler's great and tragic Sixth Symphony. Gut strings, wooden flutes, piercing non-vibrato oboes, reedy bassoons, period percussion et al ... all add up to what is not merely an academic experiment but a highly convincing musical experience - an escape from a strange elephantiasis that has crept over orchestras in the past 60 or 70 years in the pursuit of sheer volume and power.

Authentic practice even extended to a rather unexpected playing of the national anthem - not the most likely prelude to a Mahler symphony but nevertheless resplendent in Elgar's orchestration. But from the opening sounds of the Mahler - all rattling hide-headed snare drums and sharp oboes - it was evident we were in for an exciting evening.

Wyn Morris's tempo was exactly faithful to the composer's instructions, energetic but not too energetic, though he screwed up the ratchet effectively in the development section; but what was most striking was the distinctness of the orchestral colours in their new guise - the double bassoon's reedy subterranean gurgle, narrow-bore trumpets more baleful than brilliant, a "period" gong with less noise and more tone and those warm gut strings soaring in the glorious "Alma Mahler" second subject. The scherzo was truly "weighty", a sinister note struck by those plangent woodwind instruments, thrilling in their high trills - an orchestral section restored to its proper place again. Morris's interpretation of the most heart-breaking of slow movements was not as exaggeratedly slow as that of some conductors, but any loss in intensity was outweighed by a gain in warmth; the unearthly serenity of high violins and those far-off nostalgic cowbells evoked summer mountain heights most poignantly. Morris handled the massive finale - the most difficult movement to shape properly - with aplomb; in the opening section the focused sound of a 1908 tuba was a joy and, once the driving allegro began, these pungent turn-of-the-century sounds provided a powerfully turbulent effect.

Mahler's strange, haunted psychology was rarely better expressed than in this agonised music, full of foreboding, even though written at a high point of his life - a strange premonition of what was to come? The titanic struggle, punctuated by literal hammer blows, abated only momentarily for one last glimpse of bliss from those distant bells, before the brass's solemn peroration was cut short by the final shattering blow and convulsive shudder; a grim end to an evening that was not merely technically fascinating but musically absorbing.