Sunday: In the first of two Sommerfest chamber music concerts, 11 members of the Minnesota Orchestra join clarinetist Osmo Vänskä for a terrific program that partly replicates the contents of a 1992 Vänskä CD. Carl Nielsen's "Serenade in Vain," said to reflect Nielsen's troubled marriage, and Franz Hasenöhrl's wry compression of Richard Strauss' orchestral tone poem "Till Eulenspiegel" -- funnier if you know the original -- rub shoulders with Judd Greenstein's 2006 "Four on the Floor" for string quartet ("ridiculously virtuosic," says the composer) and Brahms' unabashedly gorgeous Piano Quartet, Op. 25.