Jean-Pierre Rampal, flute, John Steele Ritter, piano; Cultural Centre Concert Hall, September 30 NO matter what the venue or the performance, when one hears a major piece of music played by the man who gave its premiere with the composer, one feels inevitably in the aura of esteem. Jean-Pierre Rampal is in that pantheon of extraordinary 20th-century musicians, and each of his concerts is an event of sorts. It was even an event in l957 when Francis Poulenc insisted that Rampal play the first performance of his Flute and Piano Sonata. The work is still one of the most beguiling, colourful and charming of all Poulenc's chamber works. Rampal made the Sonata his penultimate piece, showing that honest magic - especially in that iridescent opening theme - is hardly an ephemeral thing. Rampal played an interesting programme, but the music was more satisfying than the playing. This was partly due to the atmosphere, partly to Rampal himself. The half-filled Concert Hall was mildly depressing, and the acoustics were, as usual, unreliable.In the stalls, John Steele Ritter's piano was luminous, but Rampal in the lower registers was barely heard at all. In the first half, Rampal's famed delicate crystal tone seemed a bit furry, a little fat. The Bach and Mozart sonatas - both originally written for violin - had moments of great brilliance in the fast movements. Rampal has faultless technique and nuance of tone, but these were basically joyless performances. An exception was in a remarkable Beethoven set of 12 variations on three ''national songs''. Hearing Beethoven attempt an ''English'' harmony for a Scottish song (and doing a good job) was as amazing as his variations on a yodelling song and a Russian peasant dance. The most interesting piece on the programme was Martinu's Flute Sonata. Like the Poulenc, this was written towards the end of his life, and it encompassed all those unique Martinu harmonic transitions as well as one of the most beautiful slow movements ever composed by the Czech. The composer inserted some bird-calls in the finale, but they were composed and played with rare and captivating spontaneity.