Audio data which are read out from a compact disc drive are written into a hard disk drive (6) at a rate that is higher than an audio playback rate. The written audio data are read out at a rate which is higher than the audio playback rate, and than output to audio output interfaces (buffer memories). The audio output interfaces read out the audio data at the playback rate and output the data. Since the hard disk drive (6) can perform reading/writing at a rate which is sufficiently higher than the playback rate of audio data, monitoring is enabled while performing ripping.