Leonskaja/ Pires, Dumay, Meneses, Wigmore Hall

What a day for piano-lovers and Beethoven-lovers – Elisabeth Leonskaja for lunch, Maria João Pires for supper. Beethoven from both, stupendous playing from both, all in all generating a general sense of disbelief in this member of the audience. I mean, really! The Wigmore Hall is the epicure’s choice for music, but even by Wiggie standards this was beyond expectations.

Still more, these two grand pianists were bringing Beethoven the virtuoso pianist himself to life, turning from a display of his dynamic improvisation powers to his instinctive pleasure in the more rule-based working-out of the piano in chamber music with string soloists. And even if you might place Pires temperamentally more among the fantasists and Leonskaja more among the intellectuals, the fact that it was the Russian who was playing the improvisatory piano works only deepened the personal encounter with Beethoven's ceaselessly exploring mind that each concert offered.

Leonskaja’s lunchtime recital (broadcast live by Radio 3) took fantasy as a theme, with the 1808 G minor Fantasy – a self-declaring piece of improvisation – and the 1802 Tempest piano sonata, which is itself a highly picturesque tapestry of improvisational devices. The Fantasy is all wit and boldness, a gleeful ride by Beethoven the pianist-composer over the landscape of his own abilities, spilling out scales and arpeggios in all directions, rich chordal progressions of organ-like sonorities, noodling into new harmonic places without need to expound them formally, with his characteristically extreme range of highest and lowest notes on the keyboard. You hear bell-like motifs that he would later reform in utmost plangency in his late sonatas, you also get how the instrument of the time is being pushed beyond the key-strike towards new demands on vibrating strings. It is a merry exercise in pianistics – that was how I read Leonskaja’s playing of it.

The more so because she followed it with Berg’s first sonata, written 99 years later, and in that century these dense, sensual grabbed handfuls of notes, the haunting, crunchy blue chords, have evolved into music for a different instrument, more string than percussion, an art nouveau of piano. Like her mesmerising Chopin nocturne encore, this showed Leonskaja’s fantasy side.

It's strange to think that the Tempest Sonata, where improvisation and sonority draw together in highly romantic fashion, was not inspired by some wild Goethean experience of lightning storms and forest spooks, just a fulfilment of a publisher's commission to add to the piano repertoire. This sonata is ambiguously titled (by the publisher seeking publicity), but I fancied I heard weather in Leonskaja’s playing, rather than Shakespeare. Thunder rumbled and echoed in those dark upward-broken chords in the bass, above which the pellucid quality of the upper lines, particularly in the calm of the slow movement, gleamed like freshly washed sunlight. I can’t remain unmoved by the penetrating intelligence of this pianist and how she deploys her omnivorous Moscow technique, even if I felt an occasional longing to be more alarmed. Beethoven is a frightening composer, only deceptively reassuring.

Two velvety-toned string players elegantly laid down their cloaks under the swift, zestful feet of their pianist

Pires has spoken before of her preference for chamber music over recitals, and the evening’s chamber recital with violinist Augustin Dumay and cellist Antonio Meneses showed the Portuguese pianist gleaming with all the mastery at her disposal. The full-frontal impact was in part because the pianos were switched to substitute her very bright-toned Yamaha for Leonskaja’s rich Steinway. Even so, the tiny Pires dominated her trio with her joyfulness. Both men are longstanding collaborators live and on record with her, and it’s fascinating to hear two velvety-toned string players elegantly laying down their cloaks, as it were, under the swift, zestful feet of their pianist.

The balance between the three had a work-out in the different combinations of instruments, Beethoven’s tremendous Ghost Trio of 1808 and his sweet-natured 1812 trio movement alongside his violin and cello sonatas. No doubt about it, the fine weaving of the piano with the two string players in trio fed naturally into Pires’s ebullience, the violin and cello often fusing as one through her momentum. The celebrated slow movement of the Ghost was huge, terrifying, because of the imaginative commitment, Dumay taking his tone down to threadiest nothing, Meneses burying himself in the middle, to let the other two risk all in pursuit of something glimpsed in the dark.

Again, in the playing of the two instrumental sonatas, one heard Beethoven’s exploring of the different demands – cello and piano means (roughly) the cello occupies the middle while the piano plays above and below it, and neither rules; in the violin sonata the violin stars, the piano pushed into accompaniment. The Spring Violin Sonata has its pastoral beauties but the 1807 Cello Sonata is altogether more richly textured, an especially enjoyable complementing of tones. Meneses plays his cello with a refined, almost viola-like timbre that wound its way through Pires’s playfulness and softened the over-bright Yamaha edge.

Dumay had, to my ears, occasional intonation issues but like Meneses he has that rewarding European chamber-music mastery that concert soloists often lack, the ability to absorb and support a colleague’s sound. Finally the two string players got their chance to dominate Pires in the Brahms encore, a luscious theme and variations with violin and cello romantically in charge of the tune, the piano glistening in the background. What a joyful day of music-making.

• Pires, Dumay and Meneses play the same programme this evening at the Wigmore Hall