Amp and sub power matching

[Erotomania 0]

This may come out the most newb question on earth.

When running multiple woofers, do you need a amp that is ratted to power the RMS of each woofer or both woofers? In my case, for 2 btls, to run both off one amp do I need a 4,000RMS amp or a 2,000RMS amp? or should I just be looking at individual amps like strapping 2 sundown 1500s together?

I've been looking at the sundowns and the rockford 2000 and 4000 amps.

[johnecon2001 82]

You add the power together. So for two BTL's the total need is 4kW.