As these classical music virtuosos are wont to do, Michael Bahmann was pondering the relationship between certain keys and intervals and how they can evoke mood and response in the listener.

Nothing particularly new in that, right?

But Bahmann, the esteemed pianist/harpsichordist/organist, extrapolated that concept by comparing Bach's Well-Tempered Clavier with works by Chopin and Shostakovich. He ended up grouping six pairs of preludes and fugues by the three composers. They all share the same note clusters, but never in the same order, and the results are rich and illuminate the works in a new context.

See and hear for yourself when Bahmann performs "Affinities — Connecting Bach, Chopin and Shostakovich through Well-Tempered Clavier" Saturday in Stonington's La Grua Center as part of the facility's Music Matters series.

Michael Bahmann, Musical Matters, 5 p.m. Saturday, La Grua Center, 35 Water St., Stonington; $20 reserve online; (860) 535-2300, https://lagruacenter.org.