Gerhard Frommel regarded his piano sonatas as a miniature compendium of his entire output, reflecting a fundamentally Romantic approach melded with Stravinskian vitality. The Sixth Sonata’s poised profundity, inventiveness and structural perfection gives it a place as one of the best in its genre, its serene transparency lying between the powerfully heroic Fifth Sonata and the crystalline quality of the Seventh, Frommel’s last such work.