question about my stereo?

ok I have a pioneer vsx-818v hooked to a sony dvd player mo # dvp-ns55p via coax cable I've got the reciever set to recieve it's signal from that and i've set the player to output dolby digital, on top of that i've got two polkaudio tsi 300s for my l and r fronts and a polkaudio cs10 for my center, and two polkaudio csm's for my rears. that being said when i play cd which is hooked up with the usual analog cables the sound is loud at around -60 but when i play a dvd it starts to get loud around -30 i thought digital sound was supposed to be louder. am i missing something or is this just the way it is.