When Carnegie Hall reopened in December after a 30-week, $50 million renovation that saw the historic auditorium restored from floorboards to rafters, everyone agreed it looked beautiful. There was a new maple stage, a new floor and new plush red seats. The masonry walls, 4 ft. thick, were replastered and their gold detailings redone. Gone was the dowdy curtain that hung above the stage, obscuring a hole punched in the ceiling 40 years earlier and never repaired. Even the ushers sported handsome black-and-red uniforms designed by Ralph Lauren.
The real question, though, was, How would it sound? Opened in 1891, the...