XMMS includes a really simple interface in which it shows the most important information and the controls in a main panel to make it easier to use. Furthermore, it also includes a complete equalizer and a list of the songs that we are listening to. To sum up, the basic things necessary to be able to start playing music.
Its capacity to grow by means of plug-ins has caused it to include many codecs like MP3, OGG, WAV, WMA, FLAC, MPG, MP4 and SHN. The vast amount of add-ons that can be installed in XMMS make it a very versatile player. With the plug-ins we will be able to improve from the sound quality to the formats supported, and even install viewers, skins or sound filters.
If you need a really small but functional player, XMMS should be your option.