It is well known that Rachmaninov made extensive cuts and adjustments to his First Piano Sonata, having consulted with its first performer, Konstantin Igumnov, and approved his suggestions. Revisions of this kind were more the norm than the exception for the composer. What’s more unusual is that the original version has never been published. The new but glacially slow-moving Rachmaninov Critical Edition apparently now has the manuscript but is currently in abeyance.

Lukas Geniušas has seen the original, however, and has prepared it for this recording on Rachmaninov’s Steinway, preserved at his villa on Lake Lucerne. Geniušas is candid enough to admit that not everything in the revision was a loss, and he was tempted to make a conflation – as many, from Horowitz on, have done with the Second Sonata. What he has come up with preserves most, but not all, of the digressions and textural complexities of the original. It may not prove to be the last word but the passion of Geniušas’s advocacy certainly sets the bar high for any who may choose to follow.

It would take a full-length academic article to lay out all the differences between the versions, but in essence the first movement here emerges as even more protean, dreamy and improvisatory than we are used to, while the Lento is little changed and the finale is even more saturated and restless. Geniušas helps Rachmaninov’s instrument to sing its heart out, and even if, as he says, the treble register is not as lustrous as one might want, it is capable of unleashing considerable orchestral-scale grandeur. The same goes for the four Preludes, which Geniušas also plays in earlier versions (these have appeared in the Critical Edition): excellent showcases for both instrument and pianist.

Comparisons are odious in this instance. Anyone with more than just a passing interest in Rachmaninov will need to have this excellently recorded disc on their real or virtual shelves.