Take out the SP map, if the problem persists, then the NM map is in the wrong color profile and the hues aren't correct (surface shift)
Nimm mal die SP raus, wenn das Prob weiterhin besteht dann könnte es an der normalmap liegen, da sind dann die Farbwerte verschoben (Farbprofil)
Lass mich wissen ob die SP den Unterschied macht. (Let me know whether taking out SP remedies it)
Falls das nicht hilft komme ich nochmal auf dich zu. (If it doesn't work, i'll run you through the NM fix)
@spoonetti The maps ARE the problem in this case. There is ONE way to cause this without textures, but it's not the case here.
PS: The OP is the second problem, if your F1 doesn't work without an OP then very very likely it's the SP map causing you trouble.
I think your wall can do without a specular map, but then again, it might be the normal map that's not in correct hue. (need more info)