VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
DFX Audio Enhancer - Formerly known as DFX Audio Enhancer, FxSound Enhancer instantly boosts the sound quality of the music on your PC.
AIMP - AIMP : Free Audio Player : Официальный сайт программы
Equalizer Pie - Equalizer Pie is a free audio manipulation application for OS X.
foobar2000 - An advanced freeware audio player for the Windows platform.
FxSound - Clearer Sound for Your PC. The new FxSound boosts your sound quality, volume, clarity and bass.