XMMS an Acronym for X MultiMedia System. It is a WinAmp clone (not Port) for X11.

It can play MP3, OggVorbis, CD audio, etc, has a playlist, a graphic equalizer, and several plugin interfaces for different kinds of input, output, visualization, and other miscellaneous things.

If you are bothered by the sound quality of performance, you might want to give the libmad plugin a shot.

Probably the worst thing about XMMS is the way it does its own thing in terms of UserInterface, so behaves completely differently from any desktop-wide settings you have. For example, clicking anywhere in an xmms window will bring it to the top, but you can't so easily hide it behind windows again (unless you have click to focus and click on one of the other windows). It uses its own Themes (although some of them are quite nice) and font settings, and manages its own windows so that the close, minimise and maximise buttons don't match your WindowManager's settings (except by coincidence).