I wanted to do the same as you as i got nice results in a shop with boosted tiny terror and a bariton schecter in B but it was more of a heavy rock sound than a chunky metal sound no matter what I was trying ;). If it has an effect loop you could try some of those AMT pedals that can bypass the preamp of your orange amp. Maybe an AMT R1 to emulate some rectifier sound.
you wouldn't use the meat knife on crusty bread but, equally, the serrated knife and straight edge knife aren't going to go through raw meat as quickly