Beethoven's trios for violin, viola, and cello remain among his least-played works. They seem to point back to the occasional chamber music of the Classical period, and if they're not given the proper attention, that's exactly what they do. But Beethoven himself thought enough even of the very early String Trio in E flat major, Op. 3 (1794), to supervise a keyboard arrangement of the work in the 1810s, and the Op. 9 set heard here, composed in 1798, is almost as ambitious as the group of Op. 18 string quartets that followed it by about a year, and for which it can be seen as a kind of study. The hard, weighty performances by the Trio Zimmermann command attention for these works. Hear the way it sculpts out the jagged opening melodic material of the climactic String Trio in C minor, Op. 9/3, or lay into the quasi-orchestral finale of the first trio of the set. There's a good deal of motivic work here that forecasts the density of Beethoven's mature chamber music language. The trio's Stradivarius and Guarneri instruments boom out attractively under the care of BIS' engineers, who worked in two different spaces: the first and third trios were recorded at a former Swedish music academy, and the second at a Berlin concert hall. The sonic environment is none the worse for that, and the album is a prime pick for anyone in search of these trios, which now seem to play a greater role in Beethoven's early output than has been realized.