Time to check back in with the maverick keyboard virtuoso and composer Conrad Tao. The bookends of his latest program are Debussy’s late Études, Books I and II, deliberately conceived to test the technique of future performers. In between, Tao offers his own Keyed In (advertised as “thunderous”), as well as his arrangements of songs by Harold Arlen (“Over the Rainbow”) and Robert Schumann (“Auf einer Burg”), plus free improvisation on a multi-tonal keyboard known as the Lumatone. Prime your ears for novel dissonances and overtones. —Matthew Gurewitsch