To get the best from your loudspeakers, it's important to make sure the amplifier you are using is up to the job. Several factors have to be considered, and it's worth clarifying what they mean and how they affect the performance of a loudspeaker.
Loudspeakers tend to be quantified using Watts, but this is purely a measure of the amount of power a loudspeaker can take at its input over time, and not necessarily a measurement of how loud it might go.
Optimal Audio loudspeaker power handling is therefore quoted as Watts (AES) and Watts (Peak); Peak delivering 6dB(SPL) acoustic output higher than AES (AES2-2012 standard) and referring to the loudest transients a loudspeaker can handle without distortion.
In Watts, this means that the peak power handling of a Sub 10 for example is 1000W, four times its continuous power handling of 250W.
So, give a Sub 10 250W of continuous power and you will get 121dB(SPL) out of it if you are standing 1m away from it. It will however be able to deliver transient peaks in the audio signal at 127dB(SPL(@1m, half space)) without distortion or damage.
What this all means is that for the best performance from your loudspeaker, make sure you have an amplifier that is capable of delivering more than a loudspeaker's rated AES power handling ability at the nominal impedence of the loudspeaker - 8 Ohms in the case of all Sub speakers. A 250W amplifier will deliver 121dB(SPL) from a Sub 10 and nothing more, but a more powerful amplifier will have the headroom to deliver short musical transients at higher levels, thereby ensuring that faithful reproduction of the program material is maintained.