Anton Stepanovich Arensky and Sergei Eduardovich Bortkiewicz are hardly household names. Arensky’s delicious Piano Trio in D minor continues to keep its place on the fringes of the chamber repertoire, and the Waltz movement from his Suite for two pianos receives an occasional outing; otherwise nothing. Who has even heard of Bortkiewicz other than aficionados of the piano’s dustier repertoire?