Its the Pedal.
I just hooked mine up today brand new out of the box and it also does this. I hooked up a Boss NS-2 Noise suppressor and it got rid of the hiss. This really sucks for a $400 pedal. I will be ordering an ISP Decimator. It is a great delay and I really like the banks and the way you can setup presets. I haven't run it through my rig yet since I am still puttin it together. I should be done with it in a couple of days so we will see.