Pedals that stack with the Mad Professor Mad-Rbo

Electro-Harmonix Green Russian Big Muff

Run Electro-Harmonix Green Russian Big Muff after it and the bright edge settles into something more smooth

Catalinbread SFT

Where this leans bright, Catalinbread SFT answers back warm

Behringer Chorus Symphony

Run Behringer Chorus Symphony after Mad Professor Mad-Rbo in the signal chain, clear of Mad Professor Mad-Rbo's own gain stage

Rocktron Big Crush Compressor

Rocktron Big Crush Compressor's own smooth character is the real reason this is worth trying

Line 6 DL4 Delay Modeler

Keep Mad Professor Mad-Rbo's bright voice out front: Line 6 DL4 Delay Modeler goes after Mad Professor Mad-Rbo in the signal chain so its warm voice doesn't muddy it — goes in the amp's FX loop (or last, into a clean amp)

Caroline Guitar Company Kilobyte

Caroline Guitar Company Kilobyte's pristine voice goes after Mad Professor Mad-Rbo in the signal chain — it's not there to compete with Mad Professor Mad-Rbo's own bright character — goes in the amp's FX loop (or last, into a clean amp)