'I used to play jazz on trumpet, and when I listen to Fats Waller, I know what real joy is.' Peculiarly, this is the same Robert Taub who can sit down in the cafeteria of the institute and, with equal enthusiasm, give the most fascinating look at his own field of international recognition, one Ludwig Von Beethoven.

Why Beethoven? 'Because of the immediacy of the passion and emotion,' Taub said, carefully spooning down a tuna salad. 'There's such a wealth of sound, wealth of expression.' And were these riches actually generated by Beethoven's deafness? As an answer, Taub described the background of the 'Appassionata' Sonata, which he will play at City Hall.

'This was the most agonising time in Beethoven's career. He knew he was growing deaf - which is the worst thing that can happen to any composer.

'Friends would take him to the countryside and ask him to listen to a shepherd's pipe, and he couldn't hear it. It was so tormenting that another musician would have stopped completely, but Beethoven only worked harder.' Taub described how, from the composer's notebooks, it was known that for months Beethoven struggled with the first theme, always written in four-four. Then suddenly, after all that work, Beethoven changed the key signature to twelve-eight.

'And with this simple change in rhythm, the whole movement takes on a new dimension, a new urgency. Perhaps something itself approaching the turmoil which Beethoven was going through.' Taub has a unique position in the institute, since he has no real colleagues in his field. While the institute has hosted great minds like Albert Einstein, Thomas Mann and Robert Oppenheimer over its 65-year history, the post of artist in residence was never a major concern.

In fact, Eliot was the person before Taub to have held that position.

But in 1994, after the inauguration of a new concert hall, the authorities - without giving a reason - gave an informal interview to the pianist and offered him the job as a literal one-man band within an institution of geniuses.

The advantages are manifold. First, the companionship. While working on his Beethoven book, most problems are musical. But when Taub has historical or even scientific problems, he can lean over to his peers at nearby tables to get the answers, his colleagues being among the leading astrophysicists, philosophers, historians and biologists in the world.

That is one advantage of being artist in residence.

'The second,' said the affable American, 'is that this school is a haven. If I have an idea about a piano interpretation at two in the morning, I can get up and play my heart out. Try to do that in a New York apartment.' The third advantage, he said, is that when he plays Beethoven, he can lecture about it to an audience which has unique intelligence.

'I mean, in this cafeteria, you'll never see physicists dining with historians. They each have their own places. But when I talk about Beethoven, they come in together with hours of questions, using their own disciplines to give me new insights. And that's before the concerts.' Taub, who is recording the complete Beethoven piano cycle on Vox Records, does enjoy talking about that composer.

But he is hardly a one-trick pony, with a repertoire from Bach to the most intricate modern American composers. One of his noted fields of expertise is Russian Alexander Scriabin, whose complete piano sonatas he recorded for Hamonia Mundi.

'This is where I'll begin the concert in Hong Kong. First with some early-Scriabin music, which is like Chopin but with a really Russian sound. Then later Scriabin, which verges on the mystical.

'Did you know,' asked Taub, 'that around 1903, Scriabin wrote music for the millennium? Really. Even in those days, he pictured lasers going over continents, music which would surround the Earth, huge lights.' Scriabin apparently was encouraged by another Russian, conductor Serge Koussevitsky, to continue writing the piece. But it was never finished. Koussevitsky shrugged it off at the end.

'Even with the mystical music and lights going around the world, when it's finished, people will just go out to have a cup of coffee.' That isn't what Taub wants with his audiences. After Scriabin and Beethoven, he will finish with the challenging Brahms Variations On a Theme of Paganini.

'So why did I put Scriabin, Beethoven and Brahms together for this tour? Because I like to show the maximum musical experiences, as opposed to the minimal.' Throughout his relatively short life, Taub has tried to reach that maximum. Born in New Jersey, he began as something of a prodigy, attending both Juilliard and Princeton together. In 1981, after winning several awards, he began his concert career in earnest, making his first recording, of contemporary American music.

Since that time, he has performed with every major orchestra, recorded Beethoven, Scriabin and Schumann as well as composers like Milton Babbitt, Roger Sessions, Mel Powell and Vincent Persichetti. Several major composers have composed music for him, and this November, he will premiere Babbitt's Piano Concerto with James Levine conducting.

His study has two small pictures, of Bach and Beethoven. So are these his favourites? 'Actually, I only have two pictures, because I'm a bad decorator,' he laughed.

He also has a cartoon of a doctor speaking to a hysterical patient, saying: 'Now for this operation, we're going to use the original instruments.' Because Taub is no fan of early-music reproductions.

'Bach,' he said, 'can be played on any keyboard instrument. But the piano gives the widest palette. As for playing Beethoven on the original 1800s piano, Beethoven himself wrote, towards the end of his life, that the piano was only in its idiotic beginnings.' As Taub is intense and humorous at the same time, his leisure time has that same combination. His three children (who for some reason prefer Pop's music to pop music) play piano, violin and cello, so he has his own chamber music in his house. He is a runner and skier as well.

'When I run, I think - about music, themes, how to play a passage; anything at all.' But when it comes to the actual performance, his concentration is total and intense.

'It's difficult to describe, but when I play, unconsciously three things happen. First, I have an emotion and musical vision of what I am playing.

'Second, I put myself in the centre of the house to hear what they are hearing. And then I adjust. And because each Steinway I play is different, each time I play I adjust to the piano.

'But also, when I play, if you tapped me on the shoulders and asked me my name, I doubt if I could remember it. The intensity of feeling must be complete.' International Piano Festival: July 5 - Robert Taub plays Scriabin, Beethoven and Brahms; July 6 - Artur Pizzaro plays Schumann, Ravel and Rachmaninov; July 7 - Leslie Howard plays an all-Liszt programme; July 8 - Igor Zhukhov plays Franck, Schumann and Chopin. July 5-8, 8pm. City Hall Concert Hall. $130-$160. Call 2734 9009