Easy Answer: DFX 5.0. It will transform the music that comes out of your speakers. It does cost money, though. I'll second DFX. It makes an incredible difference in how your mp3s sound. Download it ...
I have Winamp 2.9 and the Enhancer DSP plugin. I was wondering if there was a way I could encode either a wav or mp3 file of an audio file *after* dsp effects have been applied to it by Enhanced?