I guess it depend on which amp you want to mimic. ENGL makes a Powerball pedal and I'm pretty sure I've seen a Retro Tube pedal out there too. I'd suspect that's be the closest you could get to an ENGL with a pedal.
Another option is getting a Synergy SYN1 plus Savage or Powerball module and run it through the FX loop of your current amp. They were designed by the guys at ENGL. I have both and while they don't sound 100% like the real deal amp they are very close. To me they sound great and definitely have the core ENGL tone.