This piece by Delucchi is a sophisticated display of modern contrapuntal writing based on two distinct subjects. It blends traditional fugal logic with a modern aesthetic.
At Henle 5 this is a late-intermediate piece — technically substantial, with musical demands to match. The main demands: independent voices that must each sing on their own line; precise articulation — the difference between crisp and blurred is the piece; and chord voicing — bringing out one note inside a handful of others.
Beyond that, expect fine finger independence within the hand.
Focus on keeping the two distinct thematic subjects clearly delineated in terms of articulation and voicing.
Comparable difficulty and character — good candidates for what to learn next.
A level or two down with the same spirit — ideal if this piece is still out of reach.
Where this piece's skills lead: slightly harder works making similar technical demands.
Fantasia a due Soggetti (Op.19) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 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 Fantasia a due Soggetti (Op.19) lasts about 6 minutes.
Fantasia a due Soggetti (Op.19) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Ciacona in D minor, P.41 by Johann Pachelbel, Fantasia, FVB 103 by William Byrd, Ballade en mode phrygien by Jehan Alain — see the full similar-pieces list on this page.