I've had this unit for a few years, love it but last night it started exhibiting an odd issue. Ten minutes into a one hour set, output from my cabinets went away. I'm running two MB NYC 604s so it's not an impedance issue. The DI was still working so I had signal to the PA. My first thought was a connection issue so I unplugged the speakon from the back of the head, plugged it back in and had output again. This repeated a few times until I just gave up and finished the set. My next thought is that I'm possibly overloading the input. But wouldn't that affect the DI also? Any ideas?