If I'm reading your post correctly, you manually calibrated to Avia and again to the Denon's test tones. If that is correct (and you didn't use an the Denon's autocalibration), the problem you are experiencing is because of calibrating to different source components. How do you have the DVD player connected? If it is through the analogue outs, you should calibrate to the Denon, and then calibrate to the player using the player's menu (there should be test tones there too). If you are connected digitally (TOSLink of coax)... well, I'm unsure of why there is a discrepancy. I'd default to the Denon's calibration in this case.
A last suggestion, if you are holding the meter in your hand, the proximity of your body to the meter can affect its readings. Put it on a stand and step back a few feet. Make sure your body is not between the meter and the speaker playing the test tone.
