Beethoven#s final three piano sonatas have always been a source of great fascination. Composed in 1820, the Sonata op. 109 opened the door to the future with its extreme expressivity, its abandonment of traditional techniques and its radical departure from familiar aesthetic norms. Beethoven specialist Jonathan Del Mar has competently solved the questions raised by the highly complex source material of this work headed #Sonata for the Hammerklavier# in the autograph score. The result is a reliable musical text and a Critical Commentary explaining alternative readings and editorial decisions. In addition to a reader-friendly engraving and practical page-turns, the edition is rounded off with an informative Introduction and valuable notes on historical performance practice.