Mach 1 and Mach number 2

[MightySmallElectrons]

I agree. I do hear a difference but if I hadn’t built both I would have never noticed or cared.

 

[Chuck D. Bones]

Metal film is lower noise. In high-gain pedals, it makes a difference. I use mostly MF in the audio path, sometime throwing in a Carbon Comp near the output, where it can't do any harm, just for fun.