Any solo recital from Radu Lupu comes with the baggage of a cult, and this Carnegie Hall concert was no exception. Lavish praise from the weeklies aside, there really is something to the aura that surrounds this exquisite pianist. He has a unique sound, seeming to breathe with the concert hall's very air. He no longer records, and what he plays live is rarely a repeat of what he has recorded in the past. And although the fables of a reticent, retiring pianist are overwrought for a player who gives as many concerts as he does, he creates an atmosphere in the hall unlike that which surrounds any other pianist, even those like Krystian Zimerman, Grigory Sokolov, and Martha Argerich who are similarly treated as if descended from on high. Certainly the silence in the Stern Auditorium was an indication of Lupu's ability to render the coughings and splutterings of winter flu forgotten.

With Lupu, it is the sound that fascinates. He seems rarely to produce from his Steinway. Rather, the sound emanates, often in a hazy (but in no way vague) texture, and with a quietness that defies physics to spread to the back of the hall. Incredible lightness of touch is somehow married to cavernous depth of tone, with keys depressed so truly that Lupu is able to control the sound long after other pianists have given up. That emanating sound ruminates, lamenting its own transience and yet remaining seraphic. When silkiness gives way to a bear's fist of power in the instrument's lowest octaves, as in this recital's Franck, Lupu fully reveals that his command of the piano might be gossamer to the touch, but it is impregnable underneath.

Lupu's interpretations have always been singular. They are not of the love/hate variety, for if one struggles to keep up – even at relentlessly slow tempi, as here – one can always marvel at Lupu's unique musicality. One had to do so throughout this concert, for challenging ideas about the notes as written were married to a faltering accuracy. Only at a few points did imprecision matter, particularly in Schubert's D.935 Impromptus. The second piece's trio was all over the place to no discernable effect, but the fourth suffered the most, for while Lupu's disruptive, unstable playing created an intriguingly fractured edge to this music, the coda was a mess. A very beautiful mess, to be sure, but a mess nonetheless.

The rest of the Schubert was much more ethereal than in Lupu's 1982 recording of the complete Impromptus. This was not a Lieder pianist's Schubert, such as one increasingly receives from Paul Lewis, but clearly linked to the colouristic treatment given to the Debussy Préludes in the second half. This sonata in all but name – as Schumann saw it – took forever to get through, but Lupu maintained his ability to spin an endless melody from both hands at once. Whole theses could be written on how the opening flourish of the first Impromptu matched rubato to dynamics and the shape of the phrase, or on the immaculate voicing of chords in Lupu's left hand, or indeed on the lilt and sway to the second piece's outer parts. Whimsy is not Lupu's strong suit, but the second variation of the B flat major piece charmed, before the last sparkled in its light runs high on a keyboard, barely stroked.

The unjustly neglected Franck was more remarkable still, with eloquence and grace working hand-in-hand with a firm command of the Frenchman's Lisztian writing and, especially, structure. Lupu's haze, which only occasionally worked in the Schubert, here added imperceptibly, keeping tension between the melody's individual notes. The prelude and chorale were kept in a constant state of transformation, Franck's three tableaux united under his cyclical structure entirely naturally. Lupu's fullest tone of the evening was reserved for the fugue, preceded by a truly Wagnerian transition. Mists returned, as the prelude's theme returned – somehow unexpectedly, miraculously, even if one knows this music well – before all the themes merged. The bell-like sounds of celebration produced down low in the coda, could not have been a more apt celebration of a fine, fine performance.

Prior to the performance, I was expecting the Debussy to be most successful, but for some reason the tension in the hall sagged. Perhaps it was a matter of these pieces sounding too alike in Lupu's hands, for while the foggiest and dreamiest of Debussy's vignettes (Brouillards, Feuilles mortes, Bruyères, and La terrasse des audiences du clair de lune) were superb, paintings in the air's waves, one longed for more eccentricity in Général Lavine, more pointed rhythms in La puerta del vino, and less ambivalence in Debussy's homage to a mock British gentleman. But with the sweet sadness of Canope, the fleet of Les tierces alternées, and the shimmer of Feux d'artifice, who could really complain?