I am using it with a Line 6 Flextone II amp. I hear a white noise/ hissing with any or the three FX selected, or all of them. Its terrible. The white noise is minimum if I use the CLEAN setting, and set DRIVE level very low. Hitting a string loudly makes the white noise go away momentarily until the note fades, so there is some AGC kicking in to stop the noise. But even this minimal white noise is unacceptable! When I turn unit off so its bypassed, all the noise is totally gone. So its the FX box, not the guitar or cord to the amp. (there is nothing else in the chain….its the guitar straight to the Epitome input, then on to the Line 6 input. really really disappointing. Its a new unit just bought through Amazon. The unit is defective, I guess?