Given that the Mark amps are Fender based they are an excellent pedal platform. One of my favorite drives with them or any other clean amp is the Barber Direct Drive (any variant of it).
I just threw a muff pi in front, woah. I'm thinking of doing an opamp muff for fuzz since the pi is a friends. In having nose issues with the amp though. So all the pre tubes have a shield or just v1?