DACs: Airport Express vs waveterminal vs mini-dac


I know this is impossible to quantify, but with a good stereo system (Cayin TA30 tube integrated amp & Green Mountain Audio Europa speakers), what's the magnitude of difference using the following dacs?

Airport Express (I already have the AX, and can connect it to the integrated amp with RCA's [analog])

Waveterminal U24: computer to USB to waveterminal to amp (waveterminal does the DA conversion)

Inexpensive DAC like ART DIO with waveterminal: computer to USB to waveterminal to ART DIO to amp (ART DIO does DA conversion)

Apogee mini-dac: computer to USB to mini-dac to amp

Other?

What's the best bang for the buck?
mschamberlin3865
"How the whole system sounds at the end depends on many other factors."

That goes for any set up. Especially when using a stand alone DAC. I just wanted to know if it's possible.

The next question would be, can you do it dollar for dollar, or do you have to spend more $$ to get the same sound? I already have the laptop (iBook), so that's money I don't have to spend. I would just need a hard drive, a Waveterminal and a DAC. For the money I spent on the cd player, it seems like I could get a better sounding DAC. Then it's just a matter of a couple hundred bucks for a hard drive & Waveterminal.

Or am I missing something?
Dollar for dollar, you can't do better than hard drive based transport.

Don't know much about the Mac world. Perhaps someone can shed some lights on the particulars in the Mac world, such as how to get bit-perfect digital stream out of a Mac.

The only other thing is whether the noise level from your laptop and hard drive can become a factor.
I would be using iTunes with full size files. I've considered getting a Mac Mini to run everything.

What else do I need to know?
I was afraid of the word "iTunes". On a WinPC, Foobar2000 gives better sound than iTunes in my opinion.

Again, I don't know much about the Macs. To be safe, you may want to find out how to get bit-perfect digital stream from a Mac before proceeding.

Good luck!
I have AE's going through a DAC1 to Red Rose Spirit's in my bedroom setup. Amazing, significant upgrade.