Eighteen concertos, by the composer’s own reckoning, for each of the main instruments in the Romantic symphony orchestra, and counting. And most of them derive impetus from reinventing what their respective solo instruments can do. Quality is more important than quantity or gimmicks, however, and the two works here recorded, both composed in 2011, are deeply impressive in their poetry, drama and inventive vigour.

In the Horn Concerto, the immediately striking elements are the soloist’s ‘off-colour’ natural harmonics and her perambulations around the platform, which see her at times with the cornist in the 20-piece chamber orchestra, and at times in more bizarre dialogues with the double bass or the oboe. There is a conceptual affinity here with Thea Musgrave’s Horn Concerto of 1971, and I mean that as a compliment to both composers. But the accumulating energy of the first half of Aho’s work is something all his own, as are the dance-like recovery after the becalmed central cadenza (also a signature feature of his Ninth and Fifteenth symphonies) and the shying-away from any kind of grandstand conclusion.

As for the theremin, stalwart of so many otherworldly or psychedelic film episodes, it comes with its own guarantee of what Aho calls ‘shamanistic’ magic. To this he adds the idea of a procession through the eight seasons of the Sami calendar. After several hearings I still wouldn’t mind skipping over those passages where Carolina Eyck has to sing as well as play, though the trompe l’oreille effect and her realisation of it are certainly ingenious. But rarely do more than a few seconds pass in an Aho score without something utterly transfixing in its sonic invention. By the end of ‘Midnight Sun’ – the final section – breath has well and truly been taken away.

Virtuosity in the service of imagination is the abiding impression of all Aho’s concertos, and the quality of soloists, orchestra, conductor and recording here is fully up to that of the music itself. Another outstanding issue in a magnificent series from BIS.