Alkan's '1st Recueil d'Impromptus' is a collection of challenging études that explore immense technical and expressive capabilities of the piano. These pieces demand exceptional virtuosity, often pushing the boundaries of what was considered playable.
The extreme leaps, rapid figurations, and stamina required for these pieces present significant technical hurdles.
1st Recueil d'Impromptus is rated Henle level 7 of 9 — late advanced repertoire, roughly ABRSM grade 8 and above. In the RCM system it corresponds to about level 10.
You should be comfortable at Henle level 7 — meaning you can already play level 6–7 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 1st Recueil d'Impromptus lasts about 25 minutes.
1st Recueil d'Impromptus is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.