I wanted to revive this thread because in setting up my desktop system, I find my Windows 7 desktop provides better sound, especially in the bass (and with more "life" overall at all parts of the spectrum) than my Mac Mini. I was surprised at this as the Mac Mini is often recommended. I have a Puget Custom Computer core i7 full size box ("Serenity" model) from 3 or 4 years ago with solid state drive.
My Mac mini is a core i5 from 2 years ago with regular spinning drives.
I am using the usb 2.0 output on both.