Pedals that stack with the Mr. Black Double Chorus

Univox Super-Fuzz

Univox Super-Fuzz leans toward octave, and that's a real, usable character to pair with

ZVEX Fuzz Factory

ZVEX Fuzz Factory leans toward fuzzy, and that's a real, usable character to pair with

EarthQuaker Devices Dispatch Master V2

EarthQuaker Devices Dispatch Master V2's dynamic voice goes after Mr. Black Double Chorus in the signal chain — it's not there to compete with Mr. Black Double Chorus's own modulated character — goes in the amp's FX loop (or last, into a clean amp)

Echoplex EP-3

Run Echoplex EP-3 after Mr. Black Double Chorus in the signal chain, clear of Mr. Black Double Chorus's own gain stage — goes in the amp's FX loop (or last, into a clean amp)