Ok, stupid question here, but how much bass should I reasonably expect to gain from installing an in-ceiling speaker vs open-air.

I ordered a pair of these, and I've hooked them up to a small amp on my desk, and they're just sitting on my desk propped up on their side.

Look, I know these aren't going to rattle the house with massive bass, and I'm sure the ceiling joist bay will keep some of that bass from escaping (I'm finding mixed opinions on building enclosures), but so far I'm pretty worried about the bass response from these things. The reviews all say that the bass is pretty good, but I'm wondering if that's something that will come post-install. Right now, there are some songs I'm playing on these where I know the bass parts really well and I'm not even hearing them, let alone feeling them.

Other possible problems could be my amp, which is a crappy little thing I got to power some speakers in my garage while I'm working, and the source is my computer. So I don't know where the trouble could lie.

*edit*
fyi, this is the amp I'm using. I might try to hook up an old receiver I have lying around...