Anybody else getting a loud high pitched hiss on some high gain patches. I'm using monitor out cabs off to either a matrix gt800fx or Mesa 2:100 and it happens on both. Tried all combinations of ground/lift switches, nothing is clipping, no common effects(happens with all effects off or on). Tried system reset, didn't help. Turned noise gate on/off, up/down, no difference. Firmware 1.6 but this happened on previous firmware as well. Tried different pickup combos. Different cables didn't help.
*edit* This happens on all outputs when using a power amp/cab. When using the master out and other outputs, this only happened when I disengaged the cabs.
Any help is GREATLY appreciated!