Originally Posted by beans-on-toast
Is there a ground lift at the mixing board that you can try?
A bad fitting connector shouldn't be an issue. The ground lift switch simply disconnects on of the three wires, the ground. Try jamming the switch on the amp a few times in case it is faulty. It could be that you have a bad cable running to the board. Try another one if you can.
IME, if your amp's DI has always worked well, and is acting as described in the OP, it's often a cable or channel issue outside of your amp - or a power issue...
Originally Posted by jquinn86
Pretty sure all was fine on the sound techs end of things, he seems to know his stuff. Cable is working fine with a DI box now.
He could be the world's greatest soundman, and still have a channel on his snake go bad - it happens...