You definitely won't need to add that amplifier. The Denon could power the Cerwin Vegas to the point of breaking your ears.
BTW, the wattage doubles each time the decibels increase by 3. So at a distance of 2 meters, which is 7 feet, the CVs would achieve 110 decibels when the speakers are receiving 64 watts. You should never listen to speakers that close, that loud, because you would cause serious hearing damage.