[59tweed]

I don't use equipment in the loop, and am generally inexperienced as such. Still, I will try to get the ball rolling, and perhaps someone more knowledgeable will pop in.

Have you tried removing the gear from the loop to see if it hisses? I tried it and I don't get a hiss, but that is with generally lower gain settings. So, if you are getting a hiss without any gear in the loop, you may have a setting that's kicking out all the noise, or less likely, a hardware failure. Of course, if the hiss goes away without the gear in the loop, you'll to trouble shoot in the other piece of gear.