All I use is a MG100RCD and a Gibson USA Explorer. I run the head through a 1960 A cab.
This is the best distortion sound I have been able to achieve on this head. You can get a real good modern and classic metal vibe going with this.
overdrive button on OD2
Gain at around 7 to 8 (actually more like 17 to 18, it goes up to 20)
Bass almost all the way on 10 (around 8 1/2 to 9)
Mid off or around 1 to 2, I never take it past 3
Treble at about 5 to 7 depends on your taste
Contur turned all the way up to 10 that is were it sounds the best
Volume as loud as you want it ( you can control it with the master volume)
You can add reverb as much or as little as you want, I would also keep the effects loop decible button pushed in and keep the mix control in the center.