What is this FET optocoupler doing in this Voodoo Labs Sparkle Drive? It isn't mentioned on any perf or PCB layouts I'm looking at and I've never heard of one before. It's
Voodoo Lab Sparkle Drive - Muziker
Used Voodoo Lab Sparkle Drive – No.Tom Guitars
Voodoo Lab Sparkle Drive MOD Overdrive Pedal - Heid Music