What happens if my amp doesnt have enough power for a set of subs?

Question

the guy at my local shop recommends the powerbass asa 400.2 amp with the PB ps-wb10 dual 10" sub enclosure. the box is 1000w/500w RMS and the amp puts out 400w rms for 2 channels.

to me this looks like a deficiency of 100w. does this make sense? should i get an amp that puts out 500w rms?

im new to this and learning it all pretty fast. just let me know if this makes sense to you.

Answer 1

its better not to over power sub u can break voice cord on sub betterto go lower than the watts on subs but buy a good class d amp and u will get a great sound

Answer 2

 i have a question im runnning MTX terminators and im using the amp that came with it. and the 4 speakers are connected to the car original power source and the amp cannot support the dual sub and i dont know what to do. can someone please help me out? 

thanks

B