Haha well put Tippy. Let's put it this way: if you're someone who can't stand the sound of the album, this little plugin may help. If not, (please) don't bother using it!
As for what's going on, it's not rocket science, just a little down-home DSP! :) The routine separates the L-R signal (spl0 and spl1) into mid-side channels and boosts the gain on the side channel (giving you a and b). (This is just an old analog trick for stereo expansion.) Then there's a quick-n-dirty digital filter which basically does the inverse of the bass bost on your discman. If you want to play with it, that 1.7 value adjusts how much the stereo spread is enhanced, and the 0.27 values adjust how much the bass is reduced (0 is no reduction and 1 is full reduction). Anyway, I thought it would be better to post it than not, no?