Ah looks like I read wrongly.
What's the difference between all these Muffs?
Here are my general findings for a majority of the more common Muffs:
* EHX Big Muff Pi (70's) (OOP) - Smooth, rich fuzz. Fair low end. Much variation in tone. (Volume/Tone/Sustain controls)
* EHX Big Muff Pi (USA Reissue) - Smooth, rich fuzz, better low end response than original. Currently true bypass.(V/T/S)
* Sovtek Big Muff Pi (Green) (OOP) - Harsher, deeper fuzz, well suited for bass. Vary greatly from unit to unit. (V/T/S)
* Sovtek Big Muff Pi (Black) - Smoother than Green Sovtek, harsher than USA model. Currently True Bypass (V/T/S)
* EHX Little Big Muff (70's) (OOP) - No personal experience - (Vol knob/tone switch)
* EHX Little Big Muff (Current) - Electronically identical to USA Reissue, SMT components, good bass response. True bypass.
* Muff Fuzz (70's) (OOP) - Original Muff circuit. Plugged into guitar. (On/off toggle, boost knob)
* Little Muff Pi (70's) (OOP) - Muff Fuzz in a stomp box. (On off stomp, boost knob)
* Deluxe Big Muff Pi (70's/80's) (OOP) - DC Powered Big Muff Pi and Soul Preacher Compressor in one.
* Double Muff - Two Muff Fuzzes in one box. Single or double mode. Single is smooth, double is sonic hell.
* Metal Muff w/ Top Boost - No personal experience
* Micro Metal Muff - No personal experience
* Pocket Metal Muff - No personal experience
* Muff Overdrive (Nano) - Smooth, simple, volume control only. Essentially a Little Muff Pi Reissue.
* English Muff'n - Tube based Muff-like circuit. Uses 12AX7 and 12AY7. 3 band EQ. Gain/Volume controls. Get a bit of grit or sonic hell, or anywhere in between. Expensive but worth every penny IMO.
Got all these from talkbass.