Boom 3D - Audio enhancer with 3D surround sound
Hesuvi - Hesuvi imitates the binaural sound effect of many surround virtualizations by making use of...
Letasoft Sound Booster - Boosts sound volume above maximum level
DFX Audio Enhancer - Formerly known as DFX Audio Enhancer, FxSound Enhancer instantly boosts the sound quality of the music on your PC.
FxSound - Clearer Sound for Your PC. The new FxSound boosts your sound quality, volume, clarity and bass.
Boom 2 - Boom is a simple volume booster that lets you boost the volume of your Mac and your music files.