I haven't tried the Darkglass stuff, but I've tried plenty of overdrive/distortion pedals over a lot of years. The only thing that I actually like to use for dirt is my Streamliner head. It's got three preamp tubes in the front end with both a gain and volume before the EQ section so you can get as much or as little grit as you want. The amp only weighs 6.5 lbs. and has enough oomph to handle any gig. I'd recommend picking one up even if it means selling off one or both of your other heads.