XORing different constants into the four s-boxes in such a cipher has exactly the same effect as XORing a single constant into each round function output.
The XOR of (0,0) is 0; (0,1) is 1; (1,0) is 1; and (1,1) is 0..
XOR can be used to add bits without carrying.
The argument leads to the conclusion that an omnipotent being could rationally be able to do one xor the other and still be omnipotent.
He's a real haxor, man.