Loud Hissing Noise!

Immediately after first using this product I noticed an incredibly loud hiss that would only get quieter if the input or output knobs were near off. I tried different microphones, preamps, monitors, A/D converters and nothing ended up working. I even tried removing all inputs from the unit and the hiss still remained. In general the volume of the hiss was about equal to or more than the volume of my actual input. It sounds pretty much like white noise. I had ordered two units and both of them have the same issue. Chances are I received two compressors that were part of the same bad batch - I'm not completely sure. Its quite a shame considering how the build quality is amazing and this problem seems relatively uncommon, though I would still be cautious.