An ensemble controller records a performance on a MIDI musical instrument in a data field of a MIDI file synchronously with playback of a piece of music stored in a compact disc player, and the data read-out speed is stored in the control data field of the MIDI file together with an audio identification code assigned to the piece of music reproduced; when the performance is reproduced synchronously with the playback of the compact disc player, the ensemble controller adjusts a clock signal to a frequency corresponding to the data read-out speed; while the ensemble controller is making the composite apparatus reproduce the ensemble, the magnetic disc driver clocks the time intervals between the data transmission of event codes by using the clock signal of the same frequency; this results in the perfect ensemble.