Will. Yeah he dialed it in that way. Early stuff he scooped most or all of the mids. Later stuff with Damageplan he had more mids and lower tunings...
I think he boosted the treble and bass with an equalizer too...
actually he used the blue mxr EQ as a mid booster before the amp
he used a parametric eq as a boost device before the amp too
the amps settings weren't that scooped
he used somethink like treble 4, mid 3.5, bass 9
solid state amps already sound scooped, so it's not necessary to rolloff the mids
i think you would love the peavey rockmaster preamp
it's a tube preamp, but sounds sooo good for pantera
it costs around US$200 on ebay and forums
another option is theRandall RGP1000 preamp, that costs around 120-160 dollars
it has the same exact preamp of his old amps (that sound very different from the randalls made on this decade)