Same issue here as well. What I noticed about it is that it sounds like digital clipping noise (In an analog box, if you push your signal past the headroom, you get a distorted sound, with digital, the wave form peaks are "clipped" sounding). The strange thing about it, is that the clipping sounds happen mostly when I play lightly and not when I play heavy. It's almost as if the noise floor is being raised. Like there is some sort of attenuation occurring from the guitar input. I've tried with a number of guitars, different cables, etc... I've tested this with the compressor off and on, no difference. I've owned a number of multi-effects units before and the only other one that behaved very similarly was the Ampero when if was first released.