Piano Sonatas D664, 769a & 894 – Stephen Hough (piano). Hyperion, 2022 Schubert’s  “heavenly length”, a term coined by Schumann specifically in relation to Schubert’s ‘Great’ C major Symphony,  is also very much in evidence in the late piano sonatas, whose first movements can last as long as an entire Beethoven sonata.  There is a…