Can you provide a picture of your setup?
You're blaming the amp/receiver for being 'sharp' because it's class D, but there's little scientific basis for that conclusion. What makes you think it's the amp? What makes you think a class A/B amp will be 'warm?' Amps are supposed to be neutral, not warm, not sharp.
It's more likely the issue is with your speakers and/or the room, or the placement of the speakers in the room, as others have said. That's where a picture would help a lot.
As for a soft dome tweeter, they don't necessarily sound any 'warmer' or less 'sharp' than metal dome tweeters. It depends on the particular tweeter and its implementation more than on the material used for the dome. I've owned bright/sharp speakers with soft domes and warm/dull speakers with metal domes. So that's another mistaken generalization.
As for finding a speaker that 'matches' your class D receiver, that's just about impossible to tell. There's a small chance that your class D amps do have output impedance high enough to interact with the impedance of the speakers, thus altering the speaker's frequency response. But even if that is the case, to find a 'match' you would like, you'd have to know the output impedance of your amp vs. frequency, and then you'd have to know the impedance vs frequency of every speaker you're considering, and THEN you'd have to either measure the resulting response or do some pretty sophisticated simulations to predict the altered response caused by the impedance interaction. You're going down a path that would produce a nice MSEE thesis.
