Onkyo 805 as preamp pro. Not getting db

I'm sure this may have been addressed in some previous posts but I am a newbie to the forum thing... I have 2 adcom amps powering 200wpc by 5 channels using an onkyo 805 as preamp. Sound quality is far superior but total volume output is not where it should be by a long shot. What am I missing? Is this an intellivolume issue or audessy? Just want to get this dialed in. Thanks in advance for helping a newbie...
Some Adcom amps have individual channel gain knobs, maybe they are set too low.