I believe you are talking about Car Audio, correct?
If yes, I would recomend running your subs in "parallel" depending on the impedance and number of voice coils in the subs.
I would also recomend getting a Mono Block suwoofer amp. That way you don't have to worry about the stereo power output, only the total RMS wattage.
Here's a real quick way to figure out power...but this is just a quick way, in no way am I saying its the most accurate, because you still need to know the impedance of the subs and the power going into the amp.
Amps x Volts=Watts
ex., Take the fuses that are in the amp, multiply that by the power that is going into the amp (from the car battery which should be 12 Volts)
So it will look like this: The fuse is a 30 Amp fuse, multiply that by the 12 volts and you should have roughly 360 continuos power...not Max power which means diddly squat.
Feel free to ask any questions.
