There's nothing wrong with the Denon... I just find this hilarous - I plugged both in again, and the difference is so clear to me, there's just no low end with the Denon compared to the Cambridge Audio. End of story. We watched a movie and the Denon simply couldn't deliver the same experience (my wife told me this, without knowing which was even plugged in, plus she doesn't even know which is which, she has far better ears than I do)
I think people who think all amps sound the same, are not really listening to music and are completely biased.
I'm going to get a 400W amp and see if that makes a difference.
400 watts will hook you up!