Line conditioner - how much power do I need?

I live on a military installation in a house built in the 50's. The electicity is very unstable here, with alot of brown-outs. I can't do anything about the lines, since Uncle Sam owns everything.

If I buy a line conditioner, how much power handling does it need to have? I'll plug in a CDP, active preamp and 100w x 2 power amp, and maybe a sub (250w amp onboard.)

Most of the voltage regulators/power conditioners I've seen only have continuous output of 600w or 900w.

How much power handling would a unit need for my purposes?

Thanks!