I'm not convinced there's a hardware malfunction. I do wonder if (like the Timeline apparently has) there is a design issue that makes them all a bit noisy in a situation like this. I'd love to hear a video of a rig where a semi-clean amp is used, a little hiss or normal, day-to-day, modest amount of rig noise is already present on the video, and then the H9's bypass is changed. Notice that the effect isn't even ON at any time in my video. The H9 just has a higher-than-average amount of hiss.
I do HOPE that mine is merely broken (same with the others who've reported this problem). I do really like plenty of the effects. In particular, it's a reverb juggernaut.