Sometimes a quirk of fate has the happiest results.

That was the case on Monday evening, when the Seattle Chamber Music Society's Summer Festival was coping with some unexpected personnel changes. The unexpected departure of cellist Robert deMaine (whose mother died) and violinist Stefan Milenkovich (who became ill) caused an upheaval in programming, but artistic director Toby Saks was up to the challenge.

Coincidentally, the cellist Adrian Brendel (son of famous pianist Alfred Brendel) happened to be visiting the area in order to see the instrument collection of David Fulton. The younger Brendel agreed to step in for deMaine in the Mozart G Minor Piano Quartet (K.478), and Fulton lent him one of the world's greatest Stradivarius cellos, his "Bass of Spain." Brendel proved a solidly musical and highly adaptable addition to the ensemble (violinist Mark Kaplan, violist Maurycy Banaszek and pianist Yael Weiss).

Next, the program was scheduled to provide a Debussy trio with Milenkovich, but that work was scrapped when the violinist couldn't appear. Instead, the audience heard Brahms' Clarinet Trio (Op. 114), in a performance that is one of the standouts of the festival thus far. The two artists engaged originally for the Debussy — cellist Ron Thomas and pianist Adam Neiman — now partnered clarinetist Frank Kowalsky in Brahms' demanding but lyrical trio. All the players were clearly in the same impassioned mode. Kowalsky's supple, fluid clarinet joined Thomas' tremendous strength and interpretive finesse; Neiman was at his most subtle and eloquent. The results were thrilling.

The Richard Strauss Piano Quartet (Op. 13) stayed in its original configuration, with violinist Anne Akiko Meyers (in tremendous form), violist Geraldine Walther, Israeli-born cellist Amit Peled and pianist Jeremy Denk. The performance was occasionally problematic (first-movement unisons veered out of tune, for example), but the playing was exciting enough to pull the audience right along to the finale.

The personnel changes don't stop here. Denk has withdrawn from next week's performances because of a scheduling conflict and will be replaced by Lydia Artymiw. Tonight, two players will replace deMaine: Thomas and Saks. There's never a dull moment, on the schedule or on the stage.

Melinda Bargreen: mbargreen@seattletimes.com