What a BBE Sonic Maximizer does:
The human ear perceives different frequencies as being louder than one another due to how many times it repeats. Higher frequencies are smaller and repeat more often in the same amount of time than a midrange or bass frequency, and seem to cut more at lower volumes. Just turn your hi fi down really low and see what frequencies you hear the most of.
The BBE introduces a slight delay to high frequencies so that your ear perceives all of the frequencies coming out of it 'at the same time', essentially. It also adjusts the phase of the high frequencies in relation to the midrange and low freqs.
The way you would normally perceive a guitar's signal is kinda like this --
TREBLE ------------------------------>
MIDRANGE -------------------->
BASS --------------->
After the BBE, you hear it like this --
TREBLE ---------->
MIDRANGE ------>
BASS ------------>
It results in what the ear perceives as a richer, fuller tone.