Hi! Ive had my m13 unit now for a year or so and it has worked flawlessly! I love it and its my main effects unit. My issue is, I sat down to practice from a big event I have coming up in the next few days and like normal I plugged everything in as normal and switched everything on but as soon as i engaged ANY switch on the m13 it cuts all my signal and sends an awful hum that simply doesn't let anything else through at all. I've tried multiple cables and different scenes on the unit and every patch does the same thing, lets through signal when the whole unit is bypassed but as soon as an fx on the unit is chosen it cuts all signal and sends a hum that can't be navigated around! Please Help!!