So I recently got GRP 5 set up on my Win 10 machine. Everything is going smoothly so far except this one problem I've run into. I get some hardcore feedback from GRP to my mixer. I'm using a Behringer 6 Channel mixer, shown below, which runs to my PC via USB labeled as "USB Audio CODEC" in the audio selection screen. I have my guitar plugged in direct to channel one via instrument/line input and my headphones in the monitor input on the mixer. I can hear my clean guitar perfectly at this point. It's when I choose the USB Audio in GRP that it pick it up and feeds back a serious high pitch tone. I just want my guitar to go in the mixer, mixer to the GRP and back to the mixer into my monitor headphone jack.