My orange Rocker 30 (2 channel el34 amp) absolutely hates any pedal including most boost pedals. They're pretty notorious about it. Something about every pedal I've ever put in front of it absolutely kills the character of the amp. The depth, the lows and mids all just disappear no matter how mild. It's still my favorite amp, nothing else sounds quite like it, but man I got rid of every pedal I had when it was my only amp. Now I have a DRRI in addition to the orange and I remember how much fun pedals can be.