1. What amp are you using?
2. Do you wanna get the crunch from your amp or crunch from boosting another overdrive/distortion?
In my head, CRUNCH is defined by overloading a tube preamp-ed amp. A booster will come in handy. Commonly available ones.... Boss GE7. Set it flat and boost up the volume. Clean boost. A real clean boost rather than getting a TS kinda pedal reducing the drive, boosting the volume just to get "CLEAN" boost. Of course the overtones are nice but calling it clean boost... man I got issues.
There are other clean booster pedals like Zvex SHO, Catalinbread Chilli Picoso, MXR Microamp etc and it'll work.