I got my Mark IV about a year ago and I've been playing it in my apartment since. However, I'm considering joining a band and would need a heavier sound to fit in that setting. After being a bit blinded by all the knobs on the front panel, I started looking at the back panel. Simply swithching to Simulclass/triode was like feeding steroids to the amp. I didn't even turn one knob in the front! I just tried D-tuning my guitar and it was instant death! Those who think Rectos are the only heavy amp from Mesa had better think again. Now if I could only get my hands on a Mesa 4x12 cab...
Amp settings are as follows:
R1: gain 6, treble 6, presence 6, master7
R1/R2 shared: bass 5, mid 6
R2: gain 10(pulled), treble 6, precense 0, master 8
Lead(harmonics): gain 8(pulled), treble 3,5, bass 3,5, mid 4,5, precense 0, master 8