This program begins with Sibelius’s gently rocking duo, followed by an alternation between Robert Fuchs and Béla Bartók: the late-Romantic Fuchs, who, with his explicit nostalgia, steps into a time machine to travel back a few decades, and Bartók, with his rugged peasant dances collected from across the Balkans. Mozart’s vigorous Duo, originally circulated under the name of Michael Haydn, then gives way to Shostakovich’s ironic, unabashed suburban waltz, and finally to the learned, austere, and rather demanding Variations by Norwegian composer Johan Halvorsen on a theme by Händel.