Can you please try creating a new Blinn shader and pick diffuse channel in the Diffuse Color slot and normal channel in Normal slot. Increase the Specular of the shader to .5 and set view mode to full. Now if you want to see the normal details only, create a GREY channel and pick it in Diffuse channel.
Is this mari 3? if yes, use mari 2.6 ;) 3.0 is a color space nightmare. Alternatively try putting a sRGB to Linear node on top of your diffuse channel and make sure all channels use the right color space.
I don't know if i can properly explain this without it being convoluted, but here goes: I've painted out the majority of my diffuse map and there are a few textures/ layers that I need to have affect the normal channel. When I copy the layer into my normal channel and apply the "height as normal" adjustment layer it…