[daros]

non invasive, light and powerful.

compatible formats.
MP1, MP2, MP3, MP4, MPC, AAC, Ogg Vorbis, FLAC / Ogg FLAC, WavPack, WAV, AIFF, AU, SND, CDDA, WMA.

http://www.foobar2000.org/

[Thomas An.]

Good find I haven't tried Foobar yet.

You could also try MediaMonkey. I have used for the past few months and it is ok (though I do not like their default blue skin and much prefer to revert it back to windows colors)

[-Adrian]

Been a foobar user for a very long time now. It has so many hidden comforts to make life easier, i can totally recommend it.