Another lame question

You can put the music files on any device you want, another computer upstairs, a network drive etc.. The iTunes software will go to that location and retrieve the files and play them. You just have to tell iTunes where the music files reside.

iTunes by itself does not sound that good, so it is a good idea to add Amarra, Pure Music or Audirvana etc.. to improve it.

You can also use iPad, iPod, iPhone to control the mini like a remote control using REMOTE app.

Steve N.
Empirical Audio

The Airport Express will output lossless bit perfect digital signals via optical output. You lose nothing by transitting sound this way if you have a good DAC on the receiving end. It will only transmit 16/44.1 and no higher but most music is CD based or less unless you have downloaded higher resolution music to your Mac. If I understand your question, you should consider keeping the AE, stream your music to it from your current Mac, get a DAC for the AE that accepts optical Toslink signals to feed to your pre-amp and you can use all the music you currently have. Steve is correct that you can improve iTunes by using Amarra, or others but you have to configure them to send signals to the AE. You may not be able to tell the difference between iTunes and the others, depending on your system.

TG - I have had AE and even modded them. A LOT of experience with it. There is something fundamentally wrong with it and I think it might be the CODEC for the ALAC conversion. No matter what you do to it, reclocking, modding including clock upgrades, it never seems to perform well. This is why I abandoned it as a modded product and I don't recommend it.

Steve N.
Empirical Audio