Actually his main amp is an XTC 101B. He blends it with his sig Randall module for his main sound. He also uses the 5150 III and an Uberschall.
I like every other record they put out.
-First one was very commercial and a bit cheesy (sorry).
-Believe was amazing and under-rated. Ahead of its time IMO.
-10,000 Fists was half good and the other half, meh.
-Indestructible was great. Best guitar solos too. This one at 2:15 rocks and great XTC tone too.
cool interview
http://www.ultimate-guitar.com/interviews/interviews/disturbed_overall_we_complement_each_other.html