There is absolutely nothing wrong with running less than rated power to any driver. Hell, there's nothing wrong with running more than rated power either. A person could destroy a 100watt speaker with 10 watts in the right scenario as well as put 5,000 watts to a speaker rated for 1,000. It's all in the design and responsibility of the person in control of the volume and gain knobs. You'll be fine running the sub with the SAZ-1500, with or without the cooling it's not going to bother a thing. As long as you're responsible with the volume and gain knob both will last you a very long time.