Francisco Tárrega's 'Bach-Sonata segunda' is a transcription of a Bach work, likely a prelude or fugue, adapted for the guitar, but commonly performed on piano. It translates Bach's contrapuntal genius and harmonic richness into a lyrical and expressive piano idiom, often with a guitar-like resonance.
Requires a singing tone and fluid arpeggiation to capture the melodic essence.
Bach-Sonata segunda is rated Henle level 7 of 9 — late advanced repertoire, roughly ABRSM grade 8 and above.
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 Bach-Sonata segunda lasts about 5 minutes.
Bach-Sonata segunda is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.