I'm not familiar with the Rogue, but the difference between a cheap receiver, an okay amp and an excellent amp feeding nice speakers should be readily apparent. I agree with the advice that you should be looking for upgrades that offer immediate, almost jaw-dropping differences, not tweaks. I won't speculate why you didn't hear a difference between the Denon and the Rogue, but the difference I heard instantly between a higher-end Denon receiver and a nice multi-channel amp was big enough that it took one minute of a/b testing to say I'm not going back.
The Dynaudio Contour 3.3's are great speakers, but they'll be using about 3% of their potential driven by the Denon. If you think you're going to be able to buy a $2000 used amp in a year or so, it may be a good buy, but I'd buy something easier to drive if you're going to be sticking with the Denon for any period of time.
The Dynaudio Contour 3.3's are great speakers, but they'll be using about 3% of their potential driven by the Denon. If you think you're going to be able to buy a $2000 used amp in a year or so, it may be a good buy, but I'd buy something easier to drive if you're going to be sticking with the Denon for any period of time.