digband

I know this is old but I am having the same issue as the OP - exact same drop in high end and slight volume when I use the fx loop. I have not amp or cab blocks because I use a real tube amp, and no matter where I moved the Send block assigned to the fx loop 1, it always does the same treble/vol drop. Also, I pulled every effect out of the external signal chain one at a time and then just plugged a single cable, both ends, to in/out in the fx loop and it still happened. Help?