While it is not an amp in a box, this pedal is very amp-like in the way it responds to your guitar. From a clean boost to that vintage tweed fuzz you get with those classic amps, this pedal will give you the amp growl that you are looking for!
The 'diode' switch flips between original diodes, which give a nice low to mid gain drive, and a pair of LEDs which, when the drive is cranked, will give a beautiful amp-like fuzz. When you roll back the volume on your guitar, the fuzz will clean right up.
The 'fat' switch was designed to boost some of the lower frequencies that can sometimes be missing in a single coil pickup guitar.