I wana get this AMP http://efobics.com/audiobahn/ to power my 12" alpine type R sub, the sub is 300 RMS 1000 Peak

would they work together?

 

I am not sure where they get the 400 x 1 on that unless, that is like max or peak. The amp would work fine but, I would only expect your sub to see 200 x 1 rms at best. That is doing the double like some amps do. 50 x 2 @ 4 ohms, 100 x 2 @ 2 ohms and 200 x 1 @ 4 ohms. Most amps can not double their 4 ohm power when run at 2 but, some can. Like I said, that amp will work fine but, there are others out there as well.