Ok, good to know what's been posted about plugging the HD500x into the L3t. Issue I'm having, I have a mic in Channel 2 and a Guitar into Channel 1. There is a cycling hiss that comes through ever so often, and the fans kick in shortly after. Is there any way to stop that? And for some reason, my guitar side comes back distorted like it's clipping out, but it is not. I have a pretty expensive fishman system in my guitar, and I've never had problems going direct into anything before. Suggestions? Thanks :)