KMid requires to work:
KDE Well, you probably already have this :-)
A sound card A good soundcard and/or external synthesizer are recommended, as the sound quality depends greatly in your soundcard, it's not the same to play the music using an FM device, than using an AWE card.
If you don't have a soundcard, you can still compile KMid with MODE_DEMO_ONLYVISUAL defined and it will run as if you had one (but you'll get no music, of course :-( ).