Naxos’s six-disc survey of Sibelius’s less familiar orchestral works is in the safe hands of Finnish conductor Leif Segerstam. Judging by this first volume, it will be of interest to more than just Sibelius trainspotters. The two sets of incidental music recorded here, full of memorable melodies, raise the tantalising question of what the composer might have achieved in opera had he applied himself to it with more enthusiasm; at time they also sound like test runs for the symphonies. Segerstam has his Turku Philharmonic playing with both idiomatic, long-focused energy and poignant understatement; the first movement of the music for Järnefelt’s play Kuolema, later published separately as the Valse Triste, has rarely waltzed as sadly or as profoundly as this. The music for Adolf Paul’s play King Christian II centres on an expansive and genial Nocturne that sounds almost cinematic. There are also the rare Overture in A minor and two songs from Twelfth Night, resonantly delivered by baritone Waltteri Torikka.