As mentioned earlier, sound enhancement gadgets have a spotty past. They either worked a little magic or simply mucked things up. Generally, manufacturers aim to enhance two aspects of audio : the stereo soundstage and bass. This is achieved by stereo expansion and bass enhancement technologies. With more research into psychoacoustics, ie. how we perceive auditory information the way we do, HRTFs (Head Related Transfer Functions) have been created, resulting in a better implementation of these enhancement technologies.
The RumbleFX 3D Sound Amplifier is based on SRS Technologies' WOW and TruBass hardware. WOW improves an audio signal's image size, dynamics and immersion by inserting spatial cues. It is important to note that early bass enhancers were simple frequency boosters, similar to cranking the bass dial to maximum. This proved to be extremely ineffective in some cases, due to the limit of the speaker voice coils which simply could not physically produce such sound. Modern HRTF-based enhancers, such as the TruBass-based RumbleFX do not drive the speakers harder - they just fool your brain into "perceiving" the bass.