Why a Maximizer maximizes the volume!!!

Also maximizes signal phase shifting, distortion, sends sound to noise ratios down the tube.
Basically, on the low end they usually pick a certain frequency, reproduce it an octave lower, then add it to the original signal to give the allusion of deeper bass. On the high end, usually these boxes just sample a certain frequency, distort it, then add it to the original. About what a Aural Exciter does.
In any case, they tend to just mess up what is being put through it, from a pure sonic standpoint.
These kinds of boxes are fun because for the first 5 secs you can really hear the effect they have on the sound. After that though, it you are not too deaf (like so many DJ's are) you start noticing the bad artifacts they impart on the sound.
Generally, I have found that people how favor these kinds of boxes don't have very good equipment that can reproduce 20Hz-20kHz very accurately. These "maximizers" give the allusion of a more extended frequency response. If phoney baloney sound is what you are after, then this is your $200 box.
If you are really looking for kick ass sound though, nothing really beats just having kick ass equipment. In the case of a DJ, you need a very clean mixer, at least 50% more power than what your speakers are rated at, and some very high quality subs and horns. Eminence drivers just are not going to cut it....
Yes you can get similar effects from some creative eq approach's, but these have their own problems too. Your best bet if you are trying to get a more extended frequency response in your system, no matter if you are a DJ, a guitarist, or whatever is to get decent equipment. Then you won't need those silly little boxes that mess up the sound.
I speak with some credentials here concerning sound systems as I still do consulting work for clubs, mixing for bands, have done club sound system installs for professional companies, and have mixed sound for some very big named people. Never have I used a Sonic Maximizer, nor seen one used in a real professional sound system. It is just not needed. The systems that I have heard that used them sounded very distorted.
Good luck. Hopefully when you go to sell that box you won't get ripped too bad.
Ed Rei
Echo Star Studio
www.echostarstudio.com