tower match

I have my Sierra RAAL towers on the way, time to look for a sub. Full system when done will include Horizon center and Sierra 2's for rears. My room size is 12W 22L 8.5H. I live in a rental and will be moving in a couple years to a bigger house. WAF is not an issue so size is of no matter, at least as far as a big honkin box you gotta look at. I will eventually go dual subs. I will be setting the crossover frequencies out of my Sherbourn PT-7030. I haven't had a chance to play with that yet, as this whole system is new. The manual recommends 80-100 Hz crossover, but i'm not sure what options I will actually have once I start perusing the menus. I've narrowed my choices down to Rhythmik and Hsu. This was based mainly on connectivity and setting options, reviews, build quality. I'm looking for final size recommendation that would best match the system. It will be 50/50 movies, music. If I had to take a hit on one or the other as far as ported or sealed, i'd rather take the hit on the HT side. Thanks up front for any suggestions or input. Almost forgot, I appologise for another thread if this has been covered before.

Your room is about the same size as mine.

If you plan on going duals, then I would start with one F15HP.

I have only one, and it does a fine job.

Thanks curtis.