T2 Effects Loop

I sent an email to Randall and they never replied, maybe you guys can help me out here.

"Hey, I just got a Randall T2 and I am having trouble setting up the effects loop... I am reading the instructions in the booklet, but they aren't exactly descriptive... Step 2 is "adjust the effects unit input level to "just peak" while playing your most aggressive licks"... what does "just peak" mean? and secondly, the effects unit volume, cannot be altered unless the return jack is plugged in, the input volume does nothing otherwise... these instructions dont seem to make sense to me. If you could get back to me with detailed instructions to help me out, i would really appreciate it. thanks!"

When trying the effects loops I also noticed some tone killing, even with no actual pedals plugged into it. With it on, it is brighter, and thinner, with less sag, mids, and smoothness.