Entering Benaroya Hall on Friday night, it sounded as if a huge party was going on upstairs. A capacity audience was happily milling around the Nordstrom Recital Hall lobby and heading in for the Seattle Chamber Music Society's Winter Festival, which has grown in scope this year.

So has the society, in fact: Earlier this month, plans for a summer Eastside festival in August were announced. Expansion is always a bit chancy, especially in tough economic times, but if ever there were a mandate, the Seattle Chamber Music Society seems to have one. Its programs consistently sell out, to the most enthusiastic audiences in the Northwest.

Friday's attractive program offered some of the great works of the chamber repertoire. The opener, Mozart's jolly "Kegelstatt" Trio, featured the liquid clarinet sound of Frank Kowalsky with two recent additions to the festival roster, violist Ulrich Eichenauer and pianist Shai Wosner. Wosner played with a nice balance of robust and delicate sound, assertive and reticent according to the music's requirements. The performance carried forward the innate good humor of the work.

Pianist Max Levinson

Violinist Scott Yoo, one of the festival's popular regulars, was featured with pianist Max Levinson (who played a President's Piano Series recital two seasons ago) in the demanding Shostakovich Op. 134 Violin Sonata. Spiky, acerbic, difficult in every way, this sonata presents formidable challenges for both players; the piano part alone verges on the cataclysmic. Both Yoo and Levinson gave the sonata a tremendous energy.

The finale, one of the icons of chamber music, was Schubert's late, great C Major String Quintet (the "cello quintet," essentially a string quartet with an extra cello). The performance was intermittently excellent but sometimes uneven; some details of interpretation had not been fully worked out. In the quiet trio section of the third movement, for example, the defects in balance and tone quality were clear in the slow, extended passage where every little lapse shows. The players were violinists James Ehnes and Carmit Zori (both clearly on the same impassioned page), violist David Harding, and cellists Toby Saks and Bion Tsang.

The ovation that followed was the kind of heartfelt applause for which festival audiences are famous: long, sustained and joyous. These are people who take real joy in music.

Review Friday night, Illsley Ball Nordstrom Recital Hall at Benaroya Hall (continuing through Sunday).

Melinda Bargreen: mbargreen@seattletimes.com