The best dual overdrive pedal so far is the Baldringer Dual Drive. Absolut boutiquee amp-like feeling and attack, can be customized in every sound shape you wanna, more a preamp than a pedal. Lots of options inside the pedal, gain/midboosts, warm modes.
Dirk Baldringer is THE german amp modder since the 80's - he worked for Accept, Rammstein, Lukather....
Check out:
http://www.baldringer.de/index.php/en/produkte-en2
https://www.youtube.com/watch?v=UH5xaEv5wl0
https://www.youtube.com/watch?v=UH5xaEv5wl0#
I played Splawn, Friedman, Steavens, ENGLs Diezel modded Marshalls, SLO a.s.o...but the Dual Drive in front of a Plexi or TTM45
is absolut equal but way more flexible. Turns a single channel into a full 3 channel setup;
Greets