What HD is getting at, is there are too many variables for you to be able to judge the difference unless they were level matched with no eq on and with the same speakers. Tweaking the volume on one, even just a little, can make a difference in the way it sounds. Otherwise it's not a real comparison. Amplifiers should all sound the same, at the same db within their capabilities.
*Edit: I actually prefer Denon for its room correction software, not because of the way it "sounds".