Unfortunately, I do not find any controls in the devices, Hardware window to control loopback. I don’t find any hardware tab or controls on the mixer screen. Further, I have tools for mr816csx 1.7.8, but do not see a DSP mix FX program. There is no reference to loopback functionality in the operation manual, either. If you could be more specific as to where I should be looking, or the specific name of function I am searching for, I would be most grateful.