I will defer to an
article I have found to be very informative . Not to wild about the author but the information is solid. Voltage gain and input sensitivity is a balancing act based on the output voltage of your pre-outs and the sensitivity and voltage gain of your amplifier. You don't want to run the pre-out wide open since that will result in clipping the signal. Your amp has more than adequate voltage gain and 1volt will drive it to max power so 3/4 to 2/3 sounds reasonable. There are tutorials on youtube that you can look in to. consumer products tend not to have these questions since its beyond an average persons understanding so they stay within certain specs.
Richard
