For a brutal metal sound, I used triode mode, treble and mids both at 3:00, presence at 11:00 or lower, gain at 3:00 on Mark IV, and EL34s. I scooped the mids on the EQ, boosted the bass sliders, but did not put the 2200 or 6600 sliders up as high as others do. The combination of these settings...