I ADORE the NYC Big Muff Pi, unfortunately it ate ALOT of space on my pedalboard. Purchased a smaller “big muff killer” from a botique pedal builder, but didn’t like it. Got the “Little Big Muff Pi” and it sounded thin so I was very skeptical when the nano came out. Bought it, and tried it side by side with my NYC Big Muff Pi and it feels and sounds extremely close, I’m very, very happy with this pedal. I’m guessing either it’s your particular unit or perhaps you don’t have the regular NYC Big Muff Pi.