A lot of us like to have what we call head room, that way we have more power on tap, as not to try to make an amp produce more that it is capable. Say you have a sub that is capable of handling 400 watts rms, we would typically have an amp that can realistically produce 800 watts rms, that way we can cleanly give said sub the power it needs to perform properly. But, with that being said, just because a given sub can take 1000 watts rms, doesn't mean one has to provide it that 1000 watts. This hobby is a lot more than just buying stuff and tossing it in your vehicle, there should be a lot of research, and thought in what you goals and intentions are. It can be enjoyable, and daunting, all at the same time. The one thing that those of us that are serious about it understand about it, is how addictive it really is. Once you get used to what you have been running, you start trying to reach the next plateau, that is to say the next new horizon. I have personally had over 20 variations in the past 10 years, and in the midst of another 'upgrade' now.