Kawai CN35 Owner's Manual page 56

Audio Record/Playback
(USB memory)
4. Selecting the audio recorder file format
Press the or VALUE buttons to select the desired audio
recorder file format (MP3 or WAV).
Over Dubbing
Format = MP3
5. Starting the audio recorder
Press a key on the keyboard, or press the PLAY/STOP button.
or or
The LED indicators for the REC and PLAY/STOP buttons will turn
on, the selected audio file will begin to play, and overdubbing
will start.
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