Austrian pianist Till Fellner is a musician on a mission: For the past two years he’s endeavored to explore and perform the entire set of thirty-two Beethoven piano sonatas. More than 100 far-flung concerts later, his musical odyssey is winding down this fall. A packed house in the relatively intimate yet vertically capacious (and somewhat toasty) confines of Boston Conservatory’s Seully Hall was treated to his detailed and nuanced interpretation of the final three of these works, Opus 109-111, on a balmy Native American Summer evening, October 12.

Beethoven conceived of his final three piano sonatas as a set. Composed in the early 1820s, these are the works of an ailing composer in his early 50s. Indeed, work on this project was interrupted for a considerable period of time by an attack of jaundice, as well as other symptoms of his inadvertent and insidious lead poisoning. He was also by this time deaf as a haddock. These considerations only serve to make his achievements that much more astounding.

Till Fellner is a boyish 38. Decked out in tails, he cuts a serious presence on stage, with sober countenance and ramrod-straight posture on the bench. This positioning results in a slightly unusual but highly effective angle of attack, with forearms oriented a bit downward. No-nonsense approach; plunges right in. Very legato tone, with liberal use of the damper pedal. At times, he actually seems to pull the notes from the instrument, an illusion reminiscent of Michael Jackson’s ‘moonwalk’ dance step.

Think of it: Thirty-two large-scale works for solo piano. Certainly a great deal of music to have under one’s belt (or fingers), between one’s ears, and in one’s soul. These pieces in particular are uniquely challenging, spanning Beethoven’s groundbreaking journey from Classicism to Romanticism. More emotionally than technically demanding, the latter sonatas especially emulate the entire spectrum of the human psyche, most specifically Beethoven’s. Indeed, the profound and introspective final three should be rated R for Romantic; definitely for mature audiences (and players) only.

Op. 109, in the ebullient key of E-Major, seems at the outset to be quite accessible: the Vivace first movement is lilting, flowing, almost shimmering. But in true Beethovenian fashion, the Prestissimo is much more forceful and rhythmically driven. The final movement is a set of variations that redefines the genre: the sweet, languorous theme is morphed into pleasantly volatile, multifaceted mutations. Forget ebb and flow, ebb and tsunami is more like it. Fellner is more than up to the challenge of these twists and turns, however, as his hyperprecise approach colors each note. Indeed, it truly seems as if he, undoubtedly like the composer himself, has weighed and considered each and every tone.

The middle sonata, Op. 110 in A-flat, similarly takes listener and player on an emotional roller coaster, from the refinement and sophistication of the opening Moderato to the controlled energy release of the Allegro. The closing fugue, meanwhile, is intellectually as well as emotionally challenging. This is an emphatic, Romantic fugue, actually not a fugue but a fugue!, as only LvB could pen. Fellner’s attention to detail was showcased as his consistently clear voicing allowed the subject line to sing out.

And then there’s 111, in the musky key of C-minor. Gott im Himmel! With this work, Beethoven breaks through to another plane altogether. This two-movement piece is 28 minutes of shockingly modern-sounding music, featuring Lisztian, Schumannic, and even Glassian overtones. The volcanic Maestoso is music for the hearing-impaired; LvB seems to revel in the percussive nature of the piano. The music changes color and emotion on a dime [or, more appropriately, pfennig], and once again Herr Fellner was more than up to the task, turning Beethoven’s raw outbursts into elegant paroxysms. The deceptively simple Arietta drifts and meanders and seems, at times, to be the musical realization of Beethoven’s introspective mutterings. Despite his admirable attention to detail, Fellner did not lose sight of the forest for the trees, as he proved more than capable of presenting this piece as a coherent whole. As the final subdued tone died away, a passionate and sustained standing ovation washed over the artist. No encore was offered; the ending was already perfect.

Will Farrell, Bill Hall, Till Fellner: just a few of the folks with double-double-l’s. Only one of these, however, can pull beautiful music out of a big black box. Till Fellner plays with sophistication and maturity; his interpretations far transcend mere technique. As his exploration of Beethoven’s piano sonata oeuvre draws to a close and he sets his sights on more contemporary and orchestral projects, one is left wondering two things: (1) Does he have any plans to record the Beethoven sonatas, and (2) Is there any possibility of a collaboration with our own BSO? Both are exciting to contemplate. . . . .

Michael Rocha is a self-described “long-ago” music teacher, a long-time music enthusiast and pianist, and a short-time Web designer: http://www.cobaltocumulus.com. He has an MS in Meteorology from MIT.