ML5 posible fault

Hi there…loops A & B , whatever pedal i put through these two loops and whatever power i use to power them , a hissing and popping sound is audible constantly.very similar to a blown tube. Occaisionally it briefly disapears if i unplug and plug back in again . could this be a fault or is it a case of mis use.

It sounds like it could be defective - did you end up returning it for warranty repair?