Last Sunday I reviewed a new double album by Andras Schiff, featuring Sonatas and other pieces by Schubert.

It's a major release which may, in some quarters, be controversial. Why? It's not the way Schiff plays the music, though his style, at its most ultra-expressive (try his recording of Beethoven's opus 90, on an earlier CD, for example) can provoke some debate. It's what he plays it on. He does not use what one pundit has already described as a "normal" piano. He uses instead a historic instrument from 1820, an instrument called a fortepiano, from earlier in the development of what we now know as the "grand piano", a gleaming and brilliantly sleek monster of an instrument.

In terms of its sound, the fortepiano is an altogether more intimate and soft-spoken creature, built more for small rooms and possibly a more domestic environment. The big, modern concert hall is an unthinkable environment for a fortepiano. And what a fortepiano actually sounds like depends very much on the instrument itself, as well as, of course, on the player. I have one absolute shocker of a recording which clatters away unmusically as though some passing delinquent, or perhaps music-lover, has casually emptied a bag of nails into the belly of the beast.

The fact is, however, that musicians, as they do, have adapted, in their technique and touch, to a very different way of playing a very different instrument in a very different sound-world. And there is a good clutch now of sophisticated world authorities in the art of playing the fortepiano and of gleaning from a score the entirely different perspectives on a piece of music that might be offered through that instrument.

Andras Schiff and Andreas Staier are two of the leading exponents who have absolutely convinced me of the artistic viability of the listening experience. It's maybe harder for some listeners and to get used to the sound-world and adapt, as I remarked in my album review last weekend. One intelligent and experienced music lover said to me recently: "I just find it difficult to listen seriously to old music played on a very old instrument, in a rather odd way, with my modern ears." I have a notion that Andras Schiff would have some sympathy with that view. He's been there, and I'll come to that shortly.

First: a word on Schiff's instrument. It dates from around 1820: in other words, around the same time that Schubert and Beethoven were actually writing the stuff. It was built in Vienna by a manufacturer called Franz Brodmann. The keyboard ranges over six octaves, and the individual keys are narrower than those of a modern piano. Beneath your feet, however, things are very different indeed. Whereas on your average domestic upright piano there will be two pedals, one for sustaining the sound, the other an effective mute, on Schiff's Brodmann fortepiano there are four pedals: a soft pedal, a "bassoon", a "moderator" and a sustaining pedal.

With the bassoon pedal, an intricately arranged strip of parchment and silk, mounted on wood, is pressed against the strings in the bass register of the instrument. It produces a buzzing sound, a bit "bassoon-y" in timbre. With the moderator pedal, a piece of cloth is inserted between the hammers and the strings, muting both the attack and the sound.

And with all four of these in consort, the overall sound world of the music assumes a different character, altogether more varied, more intimate, and with a strikingly wider variety of tonal colours. Suddenly, the absolutely even quality of sound from a modern piano, through all of its registers, and across its range, is just about gone, instead presenting the listener with, in effect, an infinitely broader tonal palette. It's an acquired taste, but a tantalising aural experience. For the listener, it offers a wholly different perspective on some of the most familiar music in the repertoire.

It might take time to become sufficiently familiar with the sound world before you can actually listen to the music without being diverted by its "special effects". It took Schiff time too. He writes an informative essay in the programme booklet, which he entitles" Confessions of a Convert", and in which he traces a path, from his dismissal and disbelief in 1980, in what he saw as fashion, faddism and "charlatanry", to 2015 where, after years of research and investigation, he now says this: "Today it's evident that my initial views were wrong and prejudiced. My knowledge of historical keyboard instruments was incomplete and perfunctory."

This is not Schiff's first outing in this genre. I refer anyone interested to his stunning 2012 ECM New Series recording, on his beloved Brodmann fortepiano, of Beethoven's Diabelli Variations. It might blow your mind, as it did mine.