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
FWIW the m-audio audiophile firewire has worked flawlessly from my iMac. Sound is not as good as from my CD player, but is fine for background music use. One day I'll upgrade it, but, it works fine. I've also been using it to slowly import my LPs into iTunes.
I live in the mountains in central Oregon. 7 miles to the nearest town of 1000.
Surely someone with a Mac can make the drive. Anyone?

I'm in Colorado now, occassionally in the Bay Area, but not anytime soon.
I have listened to the McIntosh MDA1000 DAC.

The MDA1000 is a bit "smoother" sounding than the Apogee MiniDAC. I love the way both DACs sound, but if I had to pick one to listen to for extended periods, it would be the MDA1000. The MDA1000 also upsamples to 768kHz, and it also cost 8 times more than the MiniDAC. The waveterminal seems to do a great job passing the PCM data to the MDA1000. I did not listen to the Waveterminal built in DACs, nor did I try the Waveterminal upsampling.

I did not do a blind test, so my thoughts are purely subjective.

The set up is: Apple G4 playing Apple Lossless files, USB to Waveterminal, Toslink to MDA1000, McIntosh 1201s, McIntosh XRT28s.

Sounds absolutely fantastic.
Thanks Edumke. It looks like I will be purchasing a waveterminal in the near future. Very cool. My DAC will be much more modest. However, I don't know anything different so I will still enjoy the upgrade.

If you can recall or could do a quick test, do the Edirol and the Waveterminal have pretty much the same quality when passing the signal through to the DACs? They are about the same price, but if one is definitely better than the other I would pick it.

If they are similar, I like the Waveterminal because it is smaller and doesn't have extra features I don't need. However, quality comes first.