The audience arrived to find Zankel Hall arranged as a theatre in the round, encircling a concert grand sharing the stage with a Lumatone, a MIDI controller with a keyboard resembling the left box of an accordion (or the Jankó keyboard), illuminated in ethereal pinks and blues, the room splashed with atmospheric lighting effects. Tao is a pianist who functions thrillingly within traditional classical music trappings, but it was no mere gimmick that his solo return to Carnegie Hall brought a downtown sense of avant-garde to midtown. It’s in his soul.