“The producers have hired New York musicians as on-screen extras, making for a fun peer-spotting exercise. The second season is studded with classical-world celebrity cameos, including musicians like Joshua Bell and Lang Lang, and the Grammy-winning pianist Emanuel Ax, who played the interactive video game ‘Dance Dance Revolution’ at a dive bar during one episode. Gustavo Dudamel, the wunderkind Venezuelan conductor of the Los Angeles Philharmonic, makes an appearance as a backstage handler.”