Preview: Krystian Zimerman, Bridgewater Hall, Manchester

Krystian Zimerman loves to shock. Interviewing this great and reclusive Polish pianist a few years ago, I was brought up short by his sudden assertion that sound was only a tool for creating art, not art itself. Things like timing, atmosphere, spectacle, and smell should all be regarded as integral to a concert experience, of which a recording could only communicate a part.

This only partly explains why he won't record: other reasons concern the morals of the business, and the nature of digital technology. He must now be caught live: hence the importance of his concert at the Bridgewater Hall, where, between his performances of Bach's second Partita and Beethoven's Opus 111 sonata, he replaces the keyboard in the piano with another. Mad?

In answer, Zimerman launches into a disquisition on the difference between contemporary pianos and the instruments of Bach's time. "When you make a crescendo today," he says, "there's less emotion in it than there would have been on an 18th-century instrument. It's almost impossible to play a pianissimo which is truly dramatic – but in Beethoven's time you could. The dynamic and the emotion were independent of each other". Today, they go in lockstep, and this relates to the action of the hammers.

But the hammers also relate to tuning. We use "equal temperament", purportedly equalising the intervals between the notes, but this equalisation doesn't erase the overtones which give each key its distinctive colour, and which can result in sharp aural clashes in certain modulations, thus heightening the emotional effect. Zimerman increases those overtones for Bach.

His researches have led him to a startling conclusion apropos Beethoven, whose stratospherically high writing in the late sonatas is often attributed to his deafness. Not so, says Zimerman: Beethoven listened with the aid of a stick connecting the soundboard to his teeth, thus hearing through the bone. More may be revealed in his pre-concert talk.

23 May, 7.30pm (0161 907 9000)