These two splendid sets between them contain a substantial proportion of Luigi Nono’s output in the last decade of his life: a complete studio recording of his stage work, Prometeo (subtitled “a tragedy of listening”), and the first complete recording of his Caminantes trilogy. Common to all of late Nono is a concern with sound events stripped to bare essentials: usually built on held notes and localised clusters punctuated by more discrete gestures, the music moves slowly – sometimes very slowly. Occasionally, disconcerting, more consonant sonorities are sketched, especially in Prometeo, which incorporates materials from earlier music. Not infrequently, near-silence prevails over a span of minutes. The demands made of the listener are considerable, but so, I’d argue, are the rewards.

The music makes considerable demands of the performers as well, both practically and interpretatively: with the exception of the two-violin piece ‘Hay que caminar’ sognando, all these pieces mobilise large forces, including voices, with or without live electronics. The role of the latter, incidentally, is underlined by the use of SACD technology: Nono, who was born and died in Venice, was fond of invoking the spatial, polychoral effects of the Gabrielis. Finally, the role of silence or near-silence is such that the risk involved in live recordings is very great, any extraneous noise the potential “killer” of an otherwise great performance. So in both these recordings there is a real sense of achievement, and one comes away, apart from anything else, with a profound gratitude to all concerned!

Of the two sets, the more immediately accessible is the one from Kairos, due to the greater variety of media: apart from the two-violin piece, Nono’s last completed work, it includes No hay caminos, hay que caminar…Andrei Tarkovsky, scored for seven instrumental groups, and the still longer Caminates…Ayacucho, for three orchestral groups, choir, soloists (both vocal and instrumental), organ, electronics and percussion (the role of the latter is particularly telling, and faithfully captured). The sense of scale is not markedly different in these works from that of the opera, though the spans of stillness are necessarily shorter, as a rule. In Prometeo, the avoidance of narrative doesn’t exclude some impressive build-ups: the first tre voci episode consists of single voices very gradually evolving into much louder, complex sounds. It’s a particularly moving climax, its effectiveness inversely proportional to Nono’s use of the strategy.

Both sets are essential listening and have made a deep impression on this particular listener. Both are lovingly produced: Prometeo is accompanied by two booklets, including a “listening score” in which the different text sources are colour-coded (confusingly the colour red, though advertised, is not actually used); on the Kairos set the three sections of ‘Hay que caminar’…sognando are conflated (contrary to the booklet information) onto a single track.