When in 1906 Schoenberg wrote the initial 15-instrument version of his Chamber Symphony No. 1—followed in 1935 by the orchestral arrangement—he both reacted against, and honoured the symphonic tradition. On the former point, the huge forces and lengths of late-Romantic symphonies were condensed down to a handful of musicians performing a single movement. Yet it also has a Classical structure: five clear sections, whose inner punctuations are first a scherzo, then a slow section with even a hint of Mahler about it. Likewise, of the composers who have orchestrated Schubert songs, it’s Schoenberg’s pupil Webern who was especially faithful to the orchestral forces of Schubert’s time. Wagner meanwhile may be known for his huge orchestras, but his Siegfried Idyll was written as a private birthday present for his wife Cosima, and thus originally conceived for a group of chamber musicians balancing up the staircase to her bedroom at daybreak.