See also:

Supported Media (Disc Types)
The MP3 file recording media supported by the radio are CDDA, CD-R, CD-RW, MP3, and CDDA+MP3. ...

Supported MP3 File Formats
The radio will recognize only files with the *.MP3 extension as MP3 files. Non-MP3 files named with the *.MP3 extension may cause playback problems. The radio is designed to recognize the file a ...

Playback of MP3/WMA Files
When a medium containing MP3/WMA data is loaded, the radio checks all files on the medium. If the medium contains a lot of folders or files, the radio will take more time to start playing the MP3/ ...