Have front speakers...what's next?

Assuming they cost the same....subwoofer! But, don't buy a cheap sub,
You will end up changing it when you get into movies.

You and your wife are like me and mine. We never watch movies or listen to music anywhere near reference level. And we actually just added another component to the 2 front tower speaker only setup we had. We found a subwoofer that matched our towers on craigslist and now I can officially say, if you are going to add one component, add a subwoofer. The bass that our towers put out was already great (frequency response down to 47Hz) but now that we get to hear frequencies down to 27Hz, it just made our movie watching that much better. Even at the lower to medium volumes that we watch movies and tv at, it's a noticeable difference. Our subwoofer is in a ported enclosure (port is on the bottom of the enclosure) and it has a nice rumble during movies and also sounds good for music. Since you won't be listening to music with the volume cranked up really high, I doubt you would experience any port noise, etc. that is a byproduct of some ported subwoofer enclosures. So I say get a ported one unless you come across a heck of a deal on a sealed subwoofer.
Like grasshoppers said though, don't go the super cheap route and get something like a HTIB plastic subwoofer. What kind of tower speakers do you have? I ask this, because I wouldn't get a subwoofer that was inferior (performance-wise) to my main speakers. You will notice if one component isn't nearly as good as the rest.

The typical, and likely best, HT build process is:

- 0.0, starting

- 2.0, you're here

- 2.1, get a sub; but like grasshoppers said, don't cheap out, save for longer if you have to; even if you don't listen loud, make sure it can extend to 20Hz for the full HT experience

- 3.1, get a centre; make sure it timbre matches your mains, ideally the same speaker if you can fit it in your space

- 5.1, get rears; don't need to timbre match unless you listen to a lot of muti-channel music

I say go for the Hsu stf-2. One of my friends has a Hsu sub, and it kicks out low, tight bass. Most on here would agree that Hsu subs are good, especially for the price.

I would have bought the stf-2 if I had the money in my budget, but I ended up with a Polk psw505 for a good deal on Amazon (now even cheaper at $189). I bought bookshelf speakers, so a sub was mandatory for me when I started on my ht. Now I'm getting a center.

I agree with the above progression: mains, sub, center, rears.

Go with the STF-2 over the STF-1 for sure. Only a $30 difference to go from an 8" to a 10" driver and from 32hz down to 25hz. The Hsu STF-2 is what I was going to eventually spring for if I hadn't found the sub I picked up on craigslist for a steal.

If your mains were bookshelf speakers, I would agree that you should go with a sub.

With floorstanders I don't think the choice is so clear. If you are getting good bass already, the sub represents a marginal improvemnent (Unless of course you want to feel the bass rather than just hear it).

I would get the center. That changes the whole decoding scheme and makes it more theater like rather than just extending the low frequencies.

Also, right now you can definitely get a center that matches your mains. How long will it be before you add another piece? If it will be a couple of years down the road, a matching center might be harder to find.

For movies - the difference will be huge

Ive heard the BX5s and the bass is ok, but a subs bass would be an improvement for the lower frequencies. I would say that the BR5s like the BX5s probably arent playing the lower frequencies very well so augmenting them with a capable sub would be the best path. I would go 2.1, and then when the time comes, I would highly consider surrounds next and a center channel after that. I used to run a 4.1 setup, and the stereo imaging was just as good with movies as with music, but with the benefit of surround sound for movies or blu-ray concerts.

Just a different suggestion.

Any chance you can step up to a Rythmik FV12?
http://rythmikaudio.com/FV12.html

Gotcha. Sorry, I didn't see a listed budget so I figured I'd throw it out there.

Agreed. You will definitely notice the difference and all of the frequencies you were missing while not having a sub. Besides, having the sub will do more than just play the 10hz between 35 and 25. You will set your crossover in your receiver to around 80hz and let the sub handle the duties from 80hz on down because it is better suited for strongly producing those frquencies than your towers. Then your towers can really focus on 81hz and up.

Correct - set them to small. There are many reasons to go with towers, such as they fill a large room better, there can be less of a phase issue at the crossover region and they allow you to crossover lower then 80Hz if you'd like (depends on the speaker, of course). Sub(s) and a pair of monitor-style speakers would work well too.

After I got my sub, I tested my setup with the towers set to small on the receiver and the towers set to large. I prefer the way it sounds with the towers set to large. The midbass on the towers is just too good to give up any of it. My crossover is set to 80hz.