CD: When composers such as Stravinsky and Messiaen had their formative experiences, performance was completely ephemeral. By our generation, recordings had changed that relationship with music and performance. There has been plenty of evidence in our conversations of the profound benefits of recordings for discovering repertoire, but are there any dangers or frustrations for you as a composer, or simply as a lover of music?

JA: The trouble remains that recording still implies rigidity, whether it's a download, the physical object, or whatever. You press Play and hear that recording at the same speed, the same articulation and everything as it was before, and that is very misleading. Even with someone as precise as Boulez, I’m sure on a different day he might change his mind. I’ve been very fortunate to work with a number of really wonderful conductors, but I always want them to be free to do the music as they feel it. If I think something is wildly out of tempo, and they don't show any sign of changing, then the most I might say, and then only if asked, is that I was wondering about it. Most of the time, though, I’m very happy to let them take over and interpret the music accordingly. They’re called interpreters, after all – well please go ahead and interpret. I don't write a score to be played the same way every time. Stockhausen is one of the composers whose recorded legacy was meant to establish exactly how the music should go in every respect, no argument.