Beethoven’s Piano Sonata op.106, the “Hammerklavier” Sonata, is regarded as the most complex and demanding piece among the complex and demanding works from his late period. It was not until Franz Liszt, decades after Beethoven’s death, that a pianist was able to master this sonata’s madcap technical challenges.

The version for string quartet prepared by David Plylar, a curator at the Library of Congress, was initially intended as a guide through the structural thicket of this gigantic opus. In this rendering by the Leipzig String Quartet, however, it also turns out to be an extremely revealing expansion of our musical horizons.

Two transcriptions by Beethoven’s contemporaries enrich the programme. Along with the Gewandhaus violist Peter Michael Borck, the quartet members present Beethoven’s third attempt to write an overture for his opera Leonore. At the very latest when Borck reaches for the famous offstage trumpet, the last sceptic will become a firm believer in the quintet’s symphonic qualities.

The considerably trimmer final version of the Fidelio overture impressively rounds off this extraordinary project.