Regardless of how "useless" that number is, if its value in the amp is much greater than the rms of the subs, then you are still running a chance of blowing out your subs! If your amp is 1400w-800w, and your subs are 1800w-1000w, even though the chance isn't very high, you could still blow the subs.
And note to a$$hole:
I had purchased my first set of Dual subs (the original model, I have the newer model now) from a friend with an Audiobahn amp and wiring with it for a good price off a friend, who was getting a system of much higher wattage. I was very satisfied with how these performed and I decided on purchasing the newer Dual subs seeing as I had read on how they were a good deal (my previous set of subs were stolen). Certainly they aren't the greatest subs out there, but they perform well for their cost and they look good, regardless of what you say. This was my best option, being a poor college kid and all. When I get a bit older and have more money, I will get the good stuff. For now I get what I can manage. I cheaped out on my HU as well. I got a brand I know would last me awhile, but kept things in line. I purchased it when it was on sale, and I got the most basic model. I really wanted a HU that had bass override to send all the bass to the subs, but I couldn't afford it. Sometimes you have to skimp out when there are more important things in life than quality of subwoofers, like college.
And my subs are rather loud. A middle-aged lady I was following driving a little ole late 90's Corolla sped up by 20 mph over the speed limit to get away from me the other day (while in a 30mph zone). She kept looking in her rear-view mirror, and no I WASN'T tailgating her. And speaking of rear-view mirrors, mine is half broken now thanks to my subs. Thank you and have a nice day.