What are some good free programs to add bass to real audio, mp3, or wav files?

You can use an audio editor, but normally you add bass on the playback not on the audio file itself. If you reccorded the audio yourself EQ is done on the file with an audio editor.

When I want to put a little touch (bass or treble) on WAVs recorded from old cassettes/LP's, I use SoundStream that comes with EasyCD Creator 5.x Plat. However, this is not a freeware. :( I just copy the WAV file to a new WAV file with EQ enabled and SoundStream does it real fast. The result is very satisfactory, too.

WinAMP will convert any supported file type to wave with the EQ added. Use the Disc Writer output plugin. You could also output to MP3 or WMA with the appropriate plugin.

thanx