This month’s eclectic selection of new releases includes offbeat performances of Berlioz and Mahler, a neglected masterpiece by Swiss composer Frank Martin, Bach performed in two contrasting styles, Schubert piano music, a Roussel symphony and an intriguing disc of orchestral music by a young French composer. We also have music composed by the former keyboard player of Deep Purple, Brahms’s German Requiem, a pair of rare Stravinsky ballets and a wonderful new set of Tchaikovsky’s piano concertos. Earlier delights are provided by a selection of motets sung by a renowned countertenor and a selection of Scarlatti cantatas.