Winamp DOES dampen the lyrics, however, it's only for listening. If u want to remove the lyrics, and save the file, (maybe if u just like the music) i suggest Goldwave.
U can then save the file without the vocals.
However, A LOT DEPENDS ON HOW THE SONG IS DECODED IN MP3! Some lyrics cannot be removed, they will be suppressed tho, and the quality will get reduced too. U can however fidget around with the equaliser and restore part of the quality.