Pedals that stack with the Subdecay Siren Pitch Vibrato

Electro-Harmonix Big Muff Pi

Electro-Harmonix Big Muff Pi leans toward fuzzy, and that's a real, usable character to pair with

Fulltone OCD

Fulltone OCD's own full character is the real reason this is worth trying

Boss DM-2 Delay

Put Boss DM-2 Delay after Subdecay Siren Pitch Vibrato in the signal chain, clear of Subdecay Siren Pitch Vibrato's own gain stage — goes in the amp's FX loop (or last, into a clean amp)

Carl Martin DeLayla XL

Carl Martin DeLayla XL's analog warmth voice goes after Subdecay Siren Pitch Vibrato in the signal chain — it's not there to compete with Subdecay Siren Pitch Vibrato's own modulated character — goes in the amp's FX loop (or last, into a clean amp)