As a teenager in the early 1970s I became obsessed by rumours about a reclusive misanthrope who had composed the world’s longest and most complex piano pieces, yet allegedly would not allow them to be performed. Just what did this music sound like? The few printed scores I was able to locate looked ridiculously hard, with notes spilling over on to as many as five staves in the monumental Opus clavicembalisticum (1930). Who knew that several generations of super-pianists would emerge in the following decades who could actually play this stuff, and make it sound reasonable, or even easy?

Fredrik Ullén is such a pianist. Around 15 years ago he embarked upon recording Sorabji’s 100 Transcendental Studies, and he has recently completed the cycle. Composed between 1940 and 1944, the studies encompass pieces lasting from less than a minute’s duration up to Study No 100’s mammoth 56 minute fugue on five subjects. It’s not clear whether Sorabji conceived the studies as a total entity. Did he expect the ideal listener to experience them in sequence over their eight-hour 24 minute total duration?

To my ears, smaller is better where Sorabji is concerned. I feel that his thick and fustian keyboard-writing usually achieves greater impact when doled out in modest proportions rather than epic tomes. In this sixth and final volume of Ullén’s cycle, one encounters such marked contrasts between Sorabji the focused miniaturist and Sorabji the prolix note-spinner.

For example, the nine-minute ‘Tango habanera’ (Study No 84) infuses Ravel’s and Debussy’s takes on the genre with aphoristic gestures and side comments, yet loses momentum once Sorabji’s clotted chords kick in from all directions. The micro-to-macro trajectory of Study No 99 (inspired by Bach’s Chromatic Fantasy) holds most interest in the swirling single part-writing than in the overloaded and overlong climaxes.

Knowing how interminably bombastic Sorabji’s large-scale fugal structures often turn out, I was prepared to reject the aforementioned Study No 100 sight unseen. Yet despite the music’s statically grey tonality, the first section’s wide intervals plus the syncopated push and pull of the latter part’s phrases keep your ears off guard. Section two’s motoric motif makes its strongest effect when both hands operate in the higher registers. Section three’s four-voice texture ventures into vague mud, yet abruptly changes gear with staccato chords at the 5'03" mark (disc 2 track 4). The lyricism and transparency of the six-voice interplay throughout section five sustain attention over a 20 minute span. However, the study’s concluding 12 minutes revert to Sorabji’s comfort zone of cantankerous, notey sludge.

By contrast, the shorter selections find Sorabji on point. The composer’s fondness for two-handed bitonal scales up and down the keyboard is harnessed within manageable dimensions in the three-minute Study No 87. No 86’s long legato lines sing out to touching effect through Ullén’s sensitive command of voicing and tonal differentiation. While the pianist describes No 90 as ‘an untroubled, aimlessly wandering Andante’, I find far more purpose and direction to the music’s bristling asymmetry; it somehow presages the off-balance polyrhythms of Conlon Nancarrow’s later studies for player piano. No 95 might be described as an updated Liszt Mazeppa reduced to 54 seconds, while No 96’s simultaneous lines shimmer kaleidoscopically by way of Ullén’s multi-level touch and breathtaking pedalling.

Indeed, Ullén not only exhibits his scrupulous mastery of Sorabji’s notes but fully internalises the idiom. He articulates the music’s intricate and not so easy-to-parse foreground and background layers with a sophistication bordering on clairvoyance, with a boundless portfolio of timbres, half-tints and shadings to boot. Future Sorabji studies contenders will have to work overtime to equal, let alone surpass the extraordinary pianistic and musical standards that Ullén has set throughout this cycle. If you’ve been following Ullén’s Sorabji from the start, Vol 6 is self recommending. However, newcomers to the series may find Studies Nos 1 43 (included in Vols 1 and 2) arguably more inspired and stylistically varied, as well as easier to hear in larger stretches.

As in the previous volumes, Ullén provides annotations that describe what goes on in each piece clearly and succinctly. The booklet also contains an essay on the Studies by Sorabji acolyte Kenneth Derus, whose pretentious and inchoate prose style beggars belief.