BIS has come up with the most comprehensive collection of Ligeti’s music for piano yet recorded. As well as a few unfamiliar trifles from the composer’s early years it includes an extra study, L’arrache-coeur (“Heart-breaker”), which was originally intended as No 11 (Book 2) and dedicated to György Kurtág, but ultimately replaced by the rather less striking En suspens.

Frederik Ullén has a formidable technique, taking on the extreme challenges of the studies with phenomenal precision and élan. He actually makes it all sound almost too easy, and comparing Ullén’s version of the fiendish L’escalier du diable (Book 2) with Pierre-Laurent Aimard’s (Sony, 1/97) confirms that Aimard, though slightly more deliberate in tempo, is much more weighty and dramatic. One reason for this effect could be that Ullén recorded the first two books of studies back in 1996, and his recordings here from 1998 and 2004 have a fuller sound and generally better definition than the earlier ones. Nevertheless, there’s no doubt in my mind that Aimard characterises Books 1 and 2 (so far he’s only recorded the first of the four completed studies for Book 3) more vividly than Ullén, and in Book 1, where the music is more original, more expressive than in Books 2 and 3, Aimard is supreme.

The second BIS disc covers the full complement of the early piano compositions, starting as early as 1941 – Ligeti was 18 – with four tiny, trivial pieces in which Bartók and Kodály are the obvious models. The high-point is the 11-movement Musica ricercata (1951-52), and Ullén is especially effective in the seventh movement, whose haunting melody returned in the Violin Concerto 40 years later.

In the various early works for piano duet Ullén dubs both parts, which is fine: but I was less sure about the use of this highly artificial technique for the big set of three pieces for two pianos, Monument – Self-Portrait – Movement (1976). Is the result almost too mechanical in music that needs a strong sense of danger, of resistance to mechanisation? I find the first piece rather too strenuously severe at the best of times, but Ullén and Ullén certainly make the second and third pieces imposingly dramatic and abrasively edgy. Completists will note with delight that the second disc also includes Ligeti’s Cage-inspired Bagatelles (1961): a minute and a half of silence, in three movements, movingly realised in this recording.