this is probably a ridiculously obvious one but I'm a bit dim so I'll ask just to be sure!
I get a serious buzzing sound when I plug a guitar into my DI box's high z input, and it goes away when I touch anything metal or pick the DI up off the floor, or if I plug into the ground lift input instead. Obviously this means the ground lift is working, but I just wanted to check that I'm not ignoring some problem by doing this. The SCA chassis is sitting on a power amp unfortunately due to space restrictions, but even moving it several feet away made no difference.
Thanks!