That would be considered a line level device. Most line level devices are plug and play, and you can be plugged with impunity between devices (meaning that you can't hurt anything) . HOWEVER, often there are impedance differences that can cause sonic anomalies. You would want to use the 1/4" inputs (as opposed to the XLR inputs) and you'll likely have to work with the volume controls on the devices to get the best sound. I don't own a GT8 so I cannot give you specific info but as always NO RED in the peak meters, but you can bring it up till you see the red, then back it off till no matter how hard you play there is no LED activation.
