Making an acoustic/vx recording with GB that doesn't sound terrible.

Hi, all-

I'm having a few issues making good, clean, loud, clear recordings in GB '11 using acoustic guitar, vocals, bass and occasional brushes.

The issue is my tracks sound fat, rich, clear and all they should sound like in GB.

As soon as I upload them to desktop, the sound gets tinny, high-end, the s's on my vocals all sound like snakes, and it sounds like a 1984 Fostex cassette 4-track POS.

Most vexing.

Let me tell you what I'm doing, and maybe someone has a tip or two, much appreciate!

I record in Garageband with a Neumann TLM 103 through an M-Audio interface. I know the interface doesn't match the quality of the mike and that I should get Apogee, but at the moment this is what I have, so...trying to make it work. I don't have speakers either. Used to have a pair of NS-10s but one crapped out and...pretty soon I got rid of both of them.

I upload songs to my desktop at full AIF quality - the "export projects at full loudness" is UNCHECKED - then I launch Soundbooth CS4 and make things louder, more dynamic, etc.

I usually use the "MASTERING" control, with the amount of the effect set at 50% so it doesn't go through the roof.

In my earbuds and earphones, sounds good. Ok, save, yay!

I save and close and move the tracks to iTunes.

Open tunes and tinny, crap sound. Bring the tracks into my car and they sound like I mixed them through a food processer, not anything to do with audio. All that work for nothing.

I have spent perhaps two full days on one sound, endlessly trying to get it to sound clear, loud and so on.

It seems to me that once upon a time, my tracks sounded great, so I tried to reset Soundbooth's default settings. Holding down COMMAND-OPTION-SHIFT doesn't reset preferences.

Anyway...any help appreciated, bros and sisters.

Thanks!