Music on a small scale? Not as Beethoven conceived these Op 9 Trios. Robert Simpson found it a ‘miracle’ that the need for a second violin is never suggested and agreed with a view they are ‘the locus classicus for astonishing weight and richness of sound in this medium’. The earliest sign of these attributes appears in the second subject to the opening movement of No 1, marked pianissimo. The violin plays the theme in two-note chords; the other instruments play single notes. Beethoven imposes a soft radiance to the four-part fabric of eight bars, yet the sonority isn’t any thicker. This is also an early sign of Trio Zimmermann’s mastery of the genre; whatever the part-writing, their internal equipoise offers no hint of a fourth participant.

There is no hint of caution either. These musicians are in command of the meticulously written extremes in expression, sforzandos not indiscriminately stabbed at but gauged according to the contexts in which they appear. Tempi are gauged to a nicety too, as for example the slow movement of No 2, Andante quasi allegretto, the mood ideally balanced to convey the shadows of D minor within a ‘swing’ implied by the time signature of 6/8. All third movements are marked to be played fast but the tersely compact Scherzo of No 3 – Allegro molto e vivace – offers a particular instance of Trio Zimmermann’s mettlesome musicianship. In sum, they do Beethoven proud throughout this exceptionally fine disc, enhanced by BIS’s clean SACD sound.