I can not figure this out for the life of me. Look at any great dubstep song's spectrum. The treble doesn't die off at all! Classical music doesn't even have this much treble. The spectrum just seems to have a line of sound around -40 db once you get past 500 hz, and it goes all the way to 20khz. I know distortion helps with a lot of it, but it's a CONSTANT in some peoples drops, ignoring the fact it should happen alongside the synth's notes. I sometimes even notice this in music that isn't dubstep, Like FIAB's Conquest. Where do these people get all their treble?
http://img195.imageshack.us/img195/2209/dubstepimbluespectrum.png
LOOK AT ALL THAT TREBLE DKJNSKJN