Soundcard as a pre-amp ? (and more)

[AdamZuf]

Hello friends, I would like to have your advice.

I'm building my first decent speakers setup and I will get an Israeli DIY'er to make the Seal Electronic's OPTI-MOS monoblocks amplifier. However, I need a pre-amplifier, or to say, a volume control for the amp. I've always loved the convenience of using my computer as a source. My computer is an IBM T23 laptop.

My optional sources for now are:
A. the soundcard of my IBM laptop. Many people have bashed me for this but I A/B'ed it with a Mensa DI/O with an upgraded PS on my PPA headphones amplifier, Etymotic ER-4P and Grado RS-1 headphones, and found the soundcard to edge the Mensa a bit. With the ER-4P, I have to really get it to high output to hear any hiss - my listening volume levels are far below that.
Please, no "all soundcards are crap" remarks, because for me these remarks are just as crappy.
B. I have a DI/O which I'll mod in a few days for my Sony CD3000 headphones. I love the sound of the modded DI/O and I had one before (which turned into a Mensa, which I sold because I liked the previous DI/O better for the CD3000). The DI/O outputs 7V, vs. the 800mv of the amp:

The input sensitivity of all of our designs is standardized at approximately 800 millivolts RMS for 0 dBm into 8-ohm speaker loads

So if I wanted the setup to be: USB coaxial output->DI/O->amp, I assume that volume would have to be really lowered by the computer, and this whole deal seems quite wrong and totally risky for my speakers. (setup #3 below)
Since I want to keep the DI/O especially for the CD3000, maybe I can use it in setup #4 below.
I have the Xitel Pro-Hi-Fi Link USB coaxial output to use, BTW.

The optional setups, as I see it now:
1. IBM SC->amp setup, in which volume is controlled digitally, and might be lowered (which highers the noise floor, as far as I understand).
please take into consideration that I'm still deciding on 200/400W. the 200W will be enough for my setup, but maybe I'll go for the 400W, which will blow my speakers away in full volume (It's a bit of a risk with that setup)
2. IBM SC in full volume->pre-amp->amp setup, which adds lots of stuff to the signal, not mentioning money.
3. a USB coaxial output-> modded DI/O -> amplifier.
4. a USB coaxial output-> modded DI/O -> preamp -> amplifier
This one will require the pre-amp to be able to accept 7V without clipping. My question is if most preamps can, unlike many power amps and headphones amps. If I go the pre-amplifier route, I prefer to be able to use the DI/O as well.
5. a USB soundcard with analog volume control to use as a pre-amp -> amp.

My preference is to know that setup 1 is sonicly good and safe to use, assuming that the soundcard is good, and get away without paying anything.
I have a DIY'er in Israel; so if you suggest anything, I prefer cost effective DIY projects.

Priorities:
1. Not to risk my speakers
2. Stay as low as possible with the budget
3. Get as much quality as possible, of coarse.
4. Having the W400 as a bonus to cover other options in the future - nice!

Please advice, and thank you for your time and effort to help another guy that just wants his music to sound decent, as it's supposed to be..
Adam