This may be a stupid question, but here it goes. Sy you have a back line rig(ampeg pf800 or GK MB800) and I didn't want the tone of the back line amp, does it bypass the apms preamp to plug my own preamp into the FX return? Is the FX loop in effectively an insert to the heads power section? Will this work without there being something plugged into the amplifiers instrument input? Thanks in advance -The Dr.