No, I was referring to the pre's in the external soundcard (which also amplifies the signal). Using two preamp's like you suggest, won't do anything for you, and probably just distort the signal.

So, the chain should be:

"good"room-"good"vocal/instrument-"good"mic-"good"pre-"good"soundcard-computer

It's all about getting the best signal from the beginning of your chain starting with room, vocals and instruments, run it through good analog hardware, and have good converters so you don't loose the good stuff.

I would mostly suggest compress in the computer, though it can come in handy compressing slightly on the way in. The TC Electronic's Impact Twin has built-in dsp compression & eq, and I think that more and more external soundcards feature this.

But it can come in handy to have a really good outboard compressor, preferably multi-band, aside from that, to beef up the final mix. Not so important, when you are only doing acoustic and vocals, though.

For your use, a really good mic and/or a tube pre is what will give you the most sound.

But be aware of all the cheap tube simulations out there. Below the 1k range, they most likely won't do anything for you, so if you run a low budget, it's better to stay away from them, and get that saturated effect with a plug-in (which is both cheaper and more flexible).

A good budget pre could be the Presonus Eureka, or the SPL Goldmike (which can be found fairly cheap on e-bay).

If you run higher, some of the stuff from Universal Audio (UA), like the 710 Twin-Finity, the UA Solo 610, the Great River ME-1NV (not valve) as well as an SPL Channel one, are really really good. Next step up fra those would be high end, where you can get Neve's and stuff like that.

But always try out before you buy. Experiences of sound are subjective, at least for the use in a home setup.

justmytwocents