Pedals that stack with the Zvex Mastotron

Walrus Audio EB-10

What Zvex Mastotron brings here leans toward full — that's worth building a pairing around

Xotic RC Booster

Xotic RC Booster leans toward transparent, and that's a real, usable character to pair with

Hughes & Kettner Tube Rotosphere MKII The Analog Leslie Simulator

Hughes & Kettner Tube Rotosphere MKII The Analog Leslie Simulator's transparent voice goes after Zvex Mastotron in the signal chain — it's not there to compete with Zvex Mastotron's own full character

Ashdown Studio Compressor

What Ashdown Studio Compressor brings here leans toward compressed — that's worth building a pairing around

Roland SDE-3000D

Put Roland SDE-3000D after Zvex Mastotron in the signal chain, clear of Zvex Mastotron's own gain stage — goes in the amp's FX loop (or last, into a clean amp)

Keeley Halo

Run Keeley Halo after Zvex Mastotron in the signal chain, clear of Zvex Mastotron's own gain stage — goes in the amp's FX loop (or last, into a clean amp)