CAMBRIDGE - For some time now, chamber groups have been the main laboratory for classical music innovation - maybe even music in general (rock and jazz bands are, after all, mostly chamber-size). But the Boston Chamber Music Society, celebrating its 25th season, is a throwback: venerable repertoire in a civilized milieu, presented with simple flair and camaraderie. Sunday's concert was a good example: no overarching theme to the program, just works the performers felt were worth playing.
Albert Roussel's 1929 Trio juxtaposes sprightly neoclassicism with more enigmatic, impressionistic streams. Flutist Fenwick Smith, violist Marcus Thompson, and cellist (and BCMS artistic director) Ronald Thomas had their own fascinating counterpoint: Smith's pearly tones contrasted with Thompson's sleek elegance and Thomas's wiry, taut timbre. The combination bore uncanny fruit in the second movement, a nocturnal stroll that, for all its placidity, passes through some eerie places.