HEADRUSH FRFR-108 Guide D'utilisation page 5

Example C: Two FRFR-108s (Mono)
Connect the Left (Mono) output of your HeadRush Pedalboard to the input of one FRFR-
108, and then connect the output of that FRFR-108 to the input of another.
(from Left (Mono) (from Output)
channel)
Guitar
Surge Protector
5