That this is an intensely intimate retrospective is clear from the very first item, Kurtág’s gentle, heartfelt tribute to Holliger’s harpist wife Ursula, who died in 2014. Its poignancy is all the greater since it sounds almost like an impersonation of one of Elliott Carter’s late instrumental miniatures – and Carter, who wrote so memorably for both the Holligers, had himself died just a few months before. But Kurtág, like Holliger, owes even more to the astringent yet profoundly lyrical expressiveness of Webern, and this quality often surfaces, sometimes with touches of un-Webernian irony, in works like Kurtág’s Hommage à Elliott Carter and … (Hommage à Tristan), which condenses Wagner’s sublime five-hour portrayal of death and transfiguration into a mere 40 seconds for oboe and bass clarinet. As you might imagine, every note counts!

The two most substantial works by Holliger himself are satisfyingly well contrasted. His 1999 revision of his Sonata for solo oboe (1955-56) remains the work of a phenomenally gifted student, spinning out long lines exuberantly and eloquently to show off the player’s virtuosity of breath control and digital dexterity. But Lecture for oboe and cor anglais (2015-16) is altogether more powerful in execution and original in conception. Based around seven poems by Philippe Jacottet – the poems themselves are heard in readings by the author before each of the musical ‘settings’ – Holliger packs a whole world of refined and inventive poetic play into a sequence of short movements, the longest less than six minutes. These performances, by Holliger and Marie-Lise Schüpbach, are simply astonishing in their fluency and range of colour, and the depiction of a kind of transcendent avian mayhem in the final movement, ‘Oiseaux’, has to be heard, and reheard, to be believed.

For the opposite extreme to Holliger’s six minutes of dazzlingly diverse sound patterns, you can then move on to Kurtág’s six-minute Kroó György in memoriam for contrabass clarinet, in which only a few barely audible, grief-stricken sounds drift past to disturb the silence. Kroó was a respected Hungarian musicologist and Kurtág’s tribute seems like a very personal farewell to an era of extreme delights and horrors, in which music of genuine vision and deep feeling somehow failed to be totally suppressed.