DX import looks darker than the original 3DC model (Resolv

I checked this just to confirm. The Direct3D material attribute ‘Ambient’ is not supported. Just to make this confusing, it is the 3DC ‘Diffuse’ that is not exported, which is the 3DC equivalent of Direct3D’s ‘Ambient’. 3DC’ ‘Ambient’ is Direct3D’s ‘Emissive’. This was done to match up with POVRay’s standards.

Export a model in DX format.
Import in a new scene.

It is darker than the 3DC model (it is also the case with 7.1.2).

Is it normal?

Yes, this is expected unfortunately. The DirectX format doesn’t support one of the attributes of Direct3D for some reasons. Or, at least it didn’t in the past. Maybe this has changed. I should have a look.