Parting is, they say, such sweet sorrow, and there was certainly sadness in the air at the closing evening of the Stillwater Music Festival.

Ten years ago when Brooklyn Rider launched the annual event, it was one among dozens of young, wannabe string quartets looking for an angle in an overcrowded chamber music market. Now it has the angle and its crowded professional schedule means goodbye to Stillwater, as the New York-based ensemble no longer has time to run the festival.

Thursday’s performance at Trinity Lutheran Church showed exactly why the Rider has risen through the ranks. Despite the quartet’s relaxed, contemporary styling — trim-line vests and open-neck shirts supplant traditional concert tailoring — theirs is in many ways an old-fashioned way of making chamber music, intimate and self-communing, with none of the overwrought projection and self-aggrandizement too often encountered on recital platforms.

The group’s traversal of Schubert’s “Rosamunde” quartet was delectably aerated, light- ly bowed and ­flowing with the purity of spring water over pebbles. Even in the stabbing sforzandi of the opening movement, an open temptation to chop the music to pieces, they seemed incapable of making ugly noises. The lilting, joyful finale was pure pleasure, the four players swaying happily like fiddlers at a country wedding.

The rest of the program was typical Brooklyn Rider, a mixture of the new, the unexpected and the occasionally wacky. Selections from the new disc, “Almanac,” underlined the quartet’s strong commitment to living composers. Australian Padma Newsome’s “Gaps and Gorges” was especially impressive, the gently undulating contours of the music coaxed into profile by the fluid, caressing rubato of the players. Violins and viola were wielded waist-high, like banjos, for the plinking central section “Pizzicato Parrot.”

For some, the main attraction of the evening was the eminent Swedish mezzo-soprano Anne Sofie von Otter, an elegant, loping presence in a sunburst floral smock and immaculately sculpted platinum hairdo. She has obvious star quality, but this was a strictly collegial assignment, as the quartet previewed items from a CD it will shortly make with Von Otter back in New York City.

Two numbers by Elvis Costello were particularly striking. Von Otter brought to them a voice subtly modulated from its operatic origins into that of a creamy chanteuse, vibrato planed away and used sparingly in the upper register. An excerpt from John Adams’ opera “Doctor Atomic” riveted the attention, the gorgeous arcing melodies traced with ease and exactitude, the words tellingly communicative. Elsewhere Von Otter banged a cereal bowl with a stick in quartet member Colin Jacobsen’s playful ditty about what you used to get “For Sixty Cents” in a Brooklyn coffee shop.

Reverting to four, the quartet rocked out on Jacobsen’s “Sheriff’s Leid, Sheriff’s Freude,” showing impressive bluegrass chops in the process. Then, a few heartfelt speeches later, it was all over. For the time being, anyway, these Brooklyn boys have Minnesota roots, and say they’ll soon be back in the state. When they are, go see them.

 

Terry Blain is a Minneapolis music critic.