I just upgraded to a 4pro from a 3 pro. I have a 4x10HLF cab with the tweeter. I noticed more of a hiss with the 4pro. I called ampeg tech support and told them I had my tweeter set to the 12:00 Position. He suggested setting it to either 9 or 10:00. When I did this the hiss was lower but I could still hear it. Although when I turn the tweeter all the way down the hiss goes away altogether. Does anyone know why? Could it be defective or is it just the output of the tweeter is higher with the 4 pro. Ampeg also did say because it's more powerful that there might be a little more of a hiss to it then the 3 pro. Any ideas? Should I just keep the tweeter off? or put it back up and deal with the more of a hiss? there is more of a hiss whn I'm not playing but you can't really hear it too much while I am playing. I'm also standing less then 5 feet away from the amp while I'm playing so I can fiddle with the knobs. any thoughts would be apperciated!