I think you've misunderstood what DSS666 was saying a little. What DSS666 was saying about using pedals for the bulk of OD tones was that it allows the amp to work less hard, which in turn means it can operate much cleaner because all the signal clipping is happening outside of the amp. The amp itself doesn't care what sort of sound comes through it, it will treat a clipped signal exactly the same way it treats a clean signal. This means that while your ears are hearing some heavy distortion, your amp thinks you're playing much cleaner than you actually are.
I'm not sure I agree entirely with DSS666 here, but this basic princible is pretty solid. All he's saying is that a lot of people who play metal use far too much gain from their amp (post pre-amp, if that makes any sense). If you pull it back a little then you sound much bigger because you amp still responds to the dynamics of everything you play, instead of turning everything to mush.
I hope I've helped some way,
-Benja
