Maxon OD-820 rules for this. I really liked mine when I had it but ended up liking the OD-9 the best of all even over the OD-9 Pro+. That's just my taste though, I like to put a TS bumping mids in front and scoop alot of mids on the amp. It's not a typical TS ciruit however the OD-820 is amazing, 808 + Klon, and runs on 18v all the time (lots of headroom.) I also agree the Grid Slammer is a fine OD pedal and one of the only five I liked the best on my OD hunt.