Founded in London in 1964, the Nash Ensemble’s reputation for chamber music is untainted. These recordings show why: The group brings its trademark freshness of approach to some superb music by two 19th-century composers, both women, and both until recently much neglected. While Clara Schumann was famous as a pianist, her music was unfairly overshadowed by her husband Robert’s; her Piano Trio’s third movement features a memorable main tune, beautifully played in turn by the Nash Ensemble’s pianist, violinist and cellist. The two works by Fanny Mendelssohn, sister of Felix, are if anything even more impressive. Her Piano Trio is an outpouring of full-on Romanticism, with a first movement whose whirling keyboard virtuosity shows what an impressive pianist Fanny must have been. And her String Quartet in E-flat Major is music in the same class.