I'd recommend you get a monitor/sub set up in the same price range as the yamaha monitors-- You'll enjoy mixing hip hop more with the sub and will be playing your tracks on systems with subs. You might wind up not getting the right level of bass in your mix for all systems, but a little distorted thump can do a rap track good.
And whatever interface and inexpensive preamp should be fine. Why not just get a usb interface that has an integrated mic pre? I don't know, but I don't think that a tubepre is going to really do much for your sound over a decent basic usb interface w/pres.
Get youself a pop filter and a good mic stand, too- I think they're essential for giving yourself and any 'featured guests' a good experience while recording-- a pro looking mic set up is all the bling a rapper should need to get that studio vibe going.
EDIT:
I looked up the interface they recommended- it's $200-- plus a $100 preamp, plus the speakers...
all the dude was doing was finding out a way to max out your limit... think about it. Avoid that Store Card if you can, my friend. You'll put $700 on it, and they'll turn around and raise your limit to two G's and you'll go and buy $1300 worth of whatever they tell you to....
You don't *need* much more than what you already have to make music, remember that. If I were you and making hip hop/ rap, I'd be more interested in getting something that will help me put together better beats-- like whatever the cheapest Akai MPC is (don't they make an MPD or something now for a few hundred?) or a Synth that you can build beats with. Since samplers and synths have pro-recorded and created sounds, you can trust that they'll sound pretty good without buying expensiev monitors. Just wire your computer into a good home stereo to playback stuff for your friends, and some headphones for yourself to do mixing.
Anyway, why not ask for that interface for xmas or something, and see how that does for your mic sound. The pres are already in there, and you will open up options for just $200.
