You seem to have the wrong impression on how the diffuse level value affects your diffuse maps. Pure Black values in your maps will always be black regardless of whatever the diffuse level is set to. There is a multiplicative relationship between the two, it will never be brighter than the darkest value between the two. with how your material is set up, you are essentially cutting out all the detail of your texture.
If your floor is looking washed out, it's probably a combination of your exposure being too high, your lights too bright, and your reflection glossiness value.
FYI, Unrelated to your problem at hand.
The color correction node on your bump map does absolutely nothing, 3ds max ignores color correction in the bump slot. You can test this yourself by plugging in your base map into the bump itself and it will look the same. If you want to make a proper grey scaled bump map out of your texture you will need to make a separate map in your photo editing app.