It seems its already been covered, but Active = Powered. Active/powered and passive are your two options. At the end of the day, there is no difference - a power amplifier will be powering a speaker. The difference is whether that amp is enclosed in the same physical box as the speaker cone (active / powered box) or if it is seperate (passive box + separate amplifier). Main specs to consider - the higher the SPL rating, the louder they are. Forget the watts, and whatever else - RMS, peak, etc. All that is telling you is how much power it can draw at full output - which is useful to know, but tells you jack all about how loud it will be in the real world. Weight of the speaker - don't underestimate how important this is. Unless you have a friend or two to always help, keep in mind you will have to lug these bastards around, in and out of cars, on and off of stands. Your ears - go listen to them. I've heard 10" and horn boxes kick the ass of 15" and horn boxes in the bass department. It is all about how the speaker is put together, and the only real way to make a good decision about it is to listen to it, and ideally use it in the real world. If you can, consider hiring out the model you are thinking about, so you can try it before you buy it.