confused ....

heh guyz im getting this amp of my pal for cheap:-

1000 WATT, 4 Channel, Mosfet Car Amplifier by Boss Audio
250 WATTSx4(max)
250 WATTSx2(max)
500 WATTSx2(max)
1000 WATTSx1 (max)
Has Both High Level and RCA inputs
Input Level Control
Built-in variable Crossover
Low pass filter For Use With Subs
Thermal Overload Protection
Short Circuit Protection
Gold Plated Terminals
Super Size Power Terminals
2ohm Stable

i need to know if i get 2 X JBL LCS1250W 12" subs http://international.jbl.com/car/pro...er=LNC&cat=SUB . they have a value of 400w i dont know wot that means!
does that mean if i have 2 the amp will be at full potential or am i kidding myself?

PS if a sub has a max and a rms value. what should i actually be looking at to suit my amps 500 WATTSx2(max)

PPS would a 12 inch twin sub box 1.0 cu ft be suitable ?


kind regards for all help

i have SONY XR-M500R head unit and a 10 cd changer to run this setup
the amp model was 1000n or something ( i could not find it on da net)