Beethoven :: Sonata in E flat Major opus 27/1
The clavichord as "tool" for the music of Beethoven may sound surprising to some. However, Beethoven knew the 18th century unfretted clavichord very well, as far back as his lessons with Neefe in Bonn. Of course, Vienna was a modern city of music and the pianoforte became more and more dominant, leaving other keyboard instruments behind, definitely from early 19th century on, but still, the other instruments were still very much present in daily musical live.
Moreover, until about 1800 , most keyboard music was composed for "clavier", which could be about any instrument available. Given the fact that each type of keyboard instrument has its own sound and character, it gives much possibilities for the musician to work with this music, almost as an organist who chooses his registers in function of his instrument, mood, etc..