I own almost all models of Polk Monitor Series II (Not have only Monitor 50). Reading the specs of each one I realize of this: Starting on the theory that says if we connect two speakers capable of handle 100 W each we will have a 200 W result (100 W + 100 W = 200 W). Now the specs of some speakers:
Monitor 30: 100 W. (This have 1 woofer of 5.25 inches).
Monitor 40: 125 W. (This have 2 woofers of 5.25 inches. If the above is true this one should handle 200 W).
Monitor 60: 200 W. (This have 3 Woofers of 5.25 inches. If above monitor 30 Spec is true this one should handle 300 W).
If someone know why is this I will appreciate your responses.