This is something special and I urge everyone interested in the discography of Schubert’s piano music to hear it. Unsure about the old instrument? Could it really be adequate to encompass the sonorities and range of expression in this wide selection of works, including two of Schubert’s greatest sonatas? I would say, do not hold back.

Schiff himself says he was a slow convert, from the times some 30 years ago when people took up embattled positions about ‘authenticity’, for and against, and arrogance and dogma prevailed. ‘Are you one of us?’ as Mrs Thatcher might have enquired. Schiff, on the outside looking in, saw that many of the instruments then were not in prime condition and he kept a beady eye too on the practitioners, who were often not awfully good.

But curiosity kept him interested and the joy he has always taken in playing on wonderful instruments, whatever their provenance and pedigree, with each of them individual in character, sustained him. He believes, I am sure, that there is the closest connection between an instrument and the music written for it; and while he does not deny himself the pleasure of playing Schubert on the modern piano, he counts it as important to retain the illumination and inspiration that are to be gained from the Viennese fortepiano of Schubert’s day.

There were more than a hundred makers in the city and the instrument here, from around 1820, is by Franz Brodmann, brother of the better known Joseph whose apprentice Ignaz Bösendorfer took over the firm in 1828. It came into the possession of the Austro-Hungarian imperial family, and the last Austrian emperor and Hungarian king took it with him when he was exiled to Switzerland after the First World War. Its restoration in 1965 was carefully done and András Schiff acquired it in 2010; since then its home has been the Beethoven Haus in Bonn, on loan, where this fine recording was made a year ago. Whenever he plays Schubert, he says, its sweet tone and its sound in a small hall will always remain in the back of his mind.

Its basic speaking tone is piano and of course it cannot match a modern instrument in strength and brilliance. Yet its dynamic range is wide and when the ‘moderator’ pedal is in action – there are four pedals in all – the softest ppp passages, which are not rare in Schubert, can be realised as a nuance distinct from the pianissimos produced by the soft pedal. In the other direction it is capable of a degree beyond fortissimo as well, and at all dynamic levels the sound carries, with a tender mellowness of timbre as the norm. Concert-goers found that, with a master pianist, it easily inhabited the space of the Wigmore Hall, where Schiff gave acclaimed recitals on it at the beginning of this year. If you’re quick you may be able to catch him in Oxford in August.

As we heard in his earlier recording for ECM of the Beethoven Diabelli Variations and the last set of Bagatelles (12/13), this Brodmann is no shrinking violet. It encompasses Schubert’s mighty climaxes and dramatic eruptions as well as those passages of inwardness and quietude when this composer touches us ‘like nobody else’. The point to be stressed is that nothing is lacking: instrument and music are one, ideally matched, convincing us that the one couldn’t have been written the way it is without the other. Try the exquisite Allegretto in C minor, D915, once memorably recorded by Schnabel, for a vivid sample of the world of sound that the Brodmann opens up (disc 2, tr 1); or the first-movement exposition of the B flat major Sonata, D960, for a picture of how it matches the ambition of Schubert’s writing on the broadest scale (disc 2, tr 6).

Let us not forget the messenger! I have long counted András Schiff as one of those artists able to surprise as well as delight – only the best do that. In his favoured repertories of Bach, Mozart, Beethoven and Schubert (and his Haydn, Schumann and Bartók must not be overlooked), he has shown a continual deepening of response together with many new insights, and he has kept his music-making fresh. What we have here, which is hugely welcome, has come about through work done following a realisation that his former knowledge of historical keyboard instruments had been perfunctory. I cannot think of anyone of his calibre who has mastered the fortepiano as well as the modern piano and shown such distinction on both. In Schubert he has a claim to be considered sovereign among today’s players, carrying forward the reading and interpretation of him into areas that others have not fully explored. I would not be without the recent achievements of Mitsuko Uchida, Imogen Cooper, Paul Lewis and others; nor of course of Alfred Brendel. Schiff is, perhaps, Brendel’s successor.

I like above all the way he conveys Schubert’s wonderful instinct for the sound of the instrument. This side of the composer has not perhaps been celebrated as well as it might. These days we do better at understanding how dramatic the sonatas are and the part that dark forces play in them. Certainly we underestimate Schubert if we regard him as a permanent lyricist. And I don’t believe his sonatas are bounded by the poetic melancholy and air of resignation that some players give us to excess. It’s astounding that he developed a range of piano sound in the way he did, given that he was not a virtuoso player and didn’t even own an instrument for periods of his life. This was born, surely, out of deep love for the piano of his time such as this lovely example, with its transparency as well as fullness of sound, the distinct characters of its registers – treble, middle and bass, not homogenised – and its capacity to place the elements of melody and harmony in new relationships of colour and balance. What a lot he added to piano writing. Savour and enjoy it here.