“Here’s a sonata that will challenge pianists and that one will be able to play in 50 years”: thus Beethoven is said to have written to his publisher Artaria regarding his mighty “Hammerklavier” Sonata op. 106. Given its monumental scale and extreme musical and pianistic demands, the term “Grande Sonate” seems almost an understatement. Dedicated to Archduke Rudolph of Austria, this sonata is famous not least for the seemingly unplayable autograph metronome marks in the opening movement and final...