A long time ago when the 1st Slipknot cd came out, I spoke with Mick at a show and he told me his sound was a Marshall JMP1 into a Mesa 2:90 power amp, I think. He also used the eq on some crappy Boss rack unit. I don't know if the old other guitarist played on that cd or if it was just Mick. Jim was using a Mesa DC-10 at the time live. I guess my point is their sound on the CD sounds a lot darker and sloppier than I think I could get out of my dual rec. I'm not knocking the sound... I actually really dig the vibe of the overall sound of the 1st cd. I didn't like how with each cd things started getting clearer - especially the last one where they stopped recording to tape and went with protools hahaha....
I would try setting your dual on the vintage mode - the modern mode has that extra top on the sound that makes it sound a little brighter.
As far as Static-X, I don't know anything there at all. I wouldn't be surprised to learn that it was a Line 6 or some other fully digital setup.