Keep in mind that the UA-20 does not have a MIDI synthesizer onboard, only a MIDI interface. If you have an external sound module or keyboard connected with MIDI cables you'll be able to hear something when playing a MIDI file. Otherwise it will appear to be silent playback. Also note that the MIDI settings in the Control Panel will only effect simple programs like Windows Media Player or Winamp. In sequencing programs like Cakewalk, Cubase or Logic, you will need to look through the setup preference menus and point the MIDI input/output to the UA-20 there also.