For a bare minimum set up having an analog compressor, good sound card, and the Aphex you can get some banging bass. So on to the Aphex:

Here is some basic info I found from the Aphex website:
Aural Exciter
For more than 35 years, the Aural Exciter’s patented technology has been the audio professional’s secret weapon, a powerful way to improve and enhance sonic quality more naturally than with equalization.
For individual sounds or entire mixes, the Aural Exciter brings out detail, clarity and imaging that elevates your sound without adding level. For vocals and spoken dialog, it can dramatically increase intelligibility. For individual instruments, it adds punch and presence. And on mixes, it adds power, presence and sparkle. The Aural Exciter is the ideal solution for breathing life into MP3s and other compressed audio files.
Optical Big Bottom
The Optical Big Bottom adds a deep, powerful low-frequency punch, without the unwanted level boost that comes from adding traditional EQ. Deeper, more resonant bass response with tighter articulation helps to extend low frequency power and spectrum without the build-up or driver-damaging tendencies of bass EQ.
Basicly running your sounds in the Aphex 204 will give it a bigger and better rounded sound. When I run my Bass through it I end up shacking the windows but being at the same over all volume.
My Set Up
I have the Motu Express Card connected via USB. I then connect the output of 3/4 to the aphex input and then the inputs from the aphex to the instrument ins. I then send my sub bass in. I dial in the levels by sending the volume from my motu at close to -.01 db. Then I up the Aphex Drive until the light blinks then bring it back just a hair. I usually use it for sub bass so I keep my Tune Low and mix high.
I then sometimes do a second pass with the mid and high bass if I want to do some cool effects with the harmonic exciter. It can add a clarity to the bass that is really cool, yet I try and not use it all the time.
Then I do some final eq in the mix and done. My bass is now bigger yet not "louder" in the mix. If you only have one piece of gear and you make electronic music I suggest the Aphex.
If you have used the Aphex or have questions about it please comment. Also I have a lot of articles on sound production and sound design so feel free to check them out as well.