The third solo album from German pianist Esther Birringer surveys music by 15 different composers, bringing the masters such as Bach, Beethoven, Schubert, and others into dialogue with modern voices like Lera Auerbach, Ludovico Einaudi, and Valentin Silvestrov. “The term spectrum is usually associated with physics: when white light passes through a prism, it breaks into a full rainbow of …