Good Digital Stereo Receivers How Come My Stereo Receiver Sounds Better Than My New Digital Sony STR-DG1000 ?

How come my stereo receiver sounds better than my new digital Sony STR-DG1000 ? - good digital stereo receivers

I have an old Denon stereo receiver, but I want to enjoy in a position to 5.1 sound. So I bought the Sony STR-DG1000. The problem is when I play the soundtrack on CD, I need the volume (75%) used to listen to the sound of garbage, even if I Polk speakers well. Not to mention, in conjunction with EQ audio sound more to increase the volume. These are steps that I take to get the sound I want for my new receiver? Please help