It works, but not in the way you might expect. The 600% boost is only true if you like loud sounding distortion. If your device has a weak builtin hardware chip amplifier, then this app may make the sound output of your device exceed its normal output levels. Then end result will be a loud distortion sound that could damage your speakers or headphones. More important than that, the loud distortion levels can result into unintended hearing loss issues for you with extended use. Please, be careful.