Many a jazz musician claims an affinity with Johann Sebastian Bach, but how many close the loop? Meet Dan Tepfer, who challenges himself to emulate the baroque master’s genius for improvisation and structure in real time. Tepfer’s now-classic Goldberg Variations/Variations interpolates a spontaneously crafted variation after each of the 32 written out by the composer, to dizzying effect. Whether the cell Tepfer is responding to is melodic, rhythmic, harmonic, or some combination of all of the above, each fantasy is fresh-minted; no two iterations of the program are alike. In the new Inventions/Reinventions, Tepfer propels himself into higher orbit, alternating selections from Bach’s thrice-familiar Two-Part Inventions with improvisations that follow Bach’s general template, chasing a single phrase through a labyrinth of musical possibility before circling back to the point of origin. “It requires a lot of discipline,” Tepfer says. “To put it simply, in the Goldbergs I’m responding to Bach’s text. In the Inventions, I’m responding to the concept behind. If the Goldberg are meta, the Inventions are meta meta.” —M.G.