^See, Things, now you're being helpful! Posted links and everything. That wasn't so hard was it?
@Muffin Man: That pic is of the previous revision of the sound card. The new board does not look quite like that.. Not a whole lot has changed, though, other than having two more channels. The connections are the same, but instead of soldering to the USB connector, I'd solder the ground wires to the two right-most pads in the row of five just behind the USB connector (where it says "JP1") but really it's 6 of one, 1/2 dozen of the other. It's not unheard of for the Chinese to have multiple revisions of a board in circulation at once, so yours could be one of these or something different still. No matter what, the connections should be pretty much the same.
Regarding the issues with spaghetti: IMO DIY is always awesome, even with the flaws, because you can say you built the interface yourself. It may not run quite as flawlessly as an FB3, but it does cost about 1/5 as much (including software) and you get that warm, fuzzy feeling that comes with DIY. Just food for thought. Only you can make the final call on what's best for you. All I can do is offer insight. I've been very pleased with Spaghetti since i began using it. For the price, I was blown away. I still use it more than anything else except DMX.
I think you've got a pretty good idea of what's what now Muffin Man. I'd love to see pics of your build as it progresses.
EDIT: forgot to address the Flexmod issue.. The flexmod runs TTL or analog based on the input signal. You don't have to switch it from one to the other. If you feed it an analog signal, it is analog. If you feed it a TTL signal it is TTL. The main difference is in the structure of the wave. A TTL signal is a 0-5V square wave pulse (on and off). An analog signal can have any shape and any value between 0 and 5V.
Also, I just heard from MarioMaster that if you use a Flexmod, you have to make sure that the correction amp is set to provide no more than a +5V modulation signal. Apparently, if you use a flexmod and feed it a analog modulation signal over 5V, it will continue to feed current to the diode and possibly overdrive it.