Oh stupid webpage, this forum doesn't cache your pending response so when you click on a link, then go back, what you've typed isn't saved. Crap. No offense, but this is the first forum I've encountered in a while that doesn't have this feature. :(
Anyway, to answer a few questions.
Bottom line, my budget is roughly $200 for a sub. I spent $200 on my CD player, $200 on my receiver, and about $200 on my speakers. I spent $35 on cables. I would love to have a larger budget that would get me into NAD Silver stuff and some Paradigm Reference Studio 80's, but it's just not in the cards. I don't have a "real" job yet. So, recommendations above $300 don't mean much to me as I simply cannot afford them.
That being said, the Infinity is out of my price range, though I'll check out the Pinnacle, NHT and Aperion Audio.
For what it's worth, the K-9 is a sealed sub, the only sealed sub of the three I listed. That's why it doesn't play as low, or have/require as much power, but also why I speculate that it will be able to keep up better with the music.
If anyone has any opinions comparing these subs that I listed, I would really appreciate it as they are the only subs I have to choose from right now. And hey, if I don't like one, I can always sell it and buy another one at a small loss (the beauty of buying decent stuff).