After a year on the global festival circuit mostly spent receiving awards and rapturous acclaim, Pianomania, one of the year’s finest documentaries, finally receives a welcome theatrical release. A film about ‘love, perfection, and a little bit of madness’, according to its directors. It turns its spotlight on a world few know even exists, let alone are familiar with.

The hero of the piece is Steinway & Sons’ chief technician and master tuner, Stefan Knüpfer. This charismatic, amiable, and highly skilled individual is the man upon whom the world’s greatest concert pianists depend in order for their instruments to reach the most exacting standards of sound. Soloists such as Lang Lang and Alfred Brendel trust Knüpfer because, as quickly becomes apparent, he is as obsessed with obtaining the perfect sound as they are. At the heart of the film is Knüpfer’s relationship with the great Pierre- Laurent Aimard as the latter prepares to record Bach’s unfinished Art of Fugue on the piano. As the modern piano post-dates Bach, the two must experiment to create the sound they believe the composer intended.

It is fascinating to see the part played by Knüpfer in the musicians’ preparations. The search for the ideal sound becomes an equal collaboration between technician and performer, and Knüpfer’s occasionally unorthodox methods serve as evidence of his passion. We learn little of his life outside his work, but to watch him subsumed in it, constantly striving for perfection, tells us more about him than any biographical details ever could.