http://hometheaterhifi.com/volume_11_3/aphex-204-big-bottom-7-2004.html
I found this yday when looking at the aphex aural exciter . I recently acquired a pair of jbl 4628b cabarets which will play with such clarity at high volumes that the apparent volume doesn't seem so great , this is one device that may possibly increase perceived loudness without actually jacking up the SPL any more , which I could hardly stand .
That article has a lot of good info in it besides the stuff about the aural exciter .