I have an object textured. All colors work well within that scene in my IPR.
When i export that object as an .ASS file and reimport it, into the same scene the gamma on the imported ASS file is brighter.
No new lights added, no lights were included in the ASS.
The ass file is just the shapes and the shaders.
Any color values will be exported using the current color manager setup. So if they look different when you load the ass file, then something's different in the scene.
First I thought it's some color space mismatch in your textures (auto generated tx vs original image), but if it's just the constant colors which don't match, then I'm not sure what's wrong. Can you send me the scene maybe, so I can take a look?