This conversation is a bit old, however, I received my H9 max a few weeks ago, I am plenty satisfied in the effeect loop but yesterday I decided to test the H9 in front of the amp for the wah mainly. I must say I am experimenting exactly the same hiss problem as afore mentioned and described. In the effect loop, no noise at all, all is perfect, but, when I try it in front of my (high gain) amp, even with no other pedal nor effect loop connected, only guitar + H9 + amp (so with no risk of ground loop beween front and effect loop), I have that strong hiss.
It does not come from the guitar (I tested with several) nor from the cables of very high grade (evidence audio). And I tested with different input levels in the H9 but it is not linked to that. I use the provided power supply (just with a plug US/EU adaptator as I am in Europe) could there be a link ?
Any idea of what I could test ? Else I will continue to use it in the loop only, not a big issue, anyway…
Thanks in advance for any idea 😉