Sorry, should have been clearer haha! It does go with the volume off on either guitar, but it makes no sense for it to then be completely silent when running it through the front of the Katana at my gig last week. If it was always there, which I expect it is, it shouldn't then just disappear? And yes, I meant when it's completely taken out and not connected to Helix at all. It happens with Gtr -> Helix -> any output it seems. I've also tried other friends guitars at church, which are silent through their own rigs, and it buzzes just as much.