My apologies, I thought the F8 had the crossover in the amp, but I guess not. The F12 does have it though, I just checked:
http://www.rythmikaudio.com/download...quickguide.pdf
The F12 is a little more expensive, though, but I think it is an intensely good subwoofer. It is also more appropriate for the crossover frequency you're looking at, as the F8 is more ideal for pairing with bookshelves that need to be crossed over much higher. The F8 can go as high as 250 Hz whereas the F12 goes up to above 150 Hz, the F12 also has the aluminum driver.