I just got an Ampeg SVT4Pro to use with my setup at church. I'm running no effects and my plan was to just use the built in compression from the SVT. The room we play in is too small to plug the SVT into a cab and then mic. as it overpowers the house, so the plan was to run Direct Out from the head into the PA. My tone is perfect and exactly what I was looking for, but when I'm not playing or even lightly underneath when I am playing is a terrible hiss. There's no ground lift on the SVT and when I went out of the SVT into a passive DI and then to the house it didn't make that big of a difference. Any thoughts on how to get rid of this hiss? Grounding issue? Polarity? Do I need to add any equipment?