Bit Perfect Audio
 

Several audio questions here. I am using Ubuntu 12.04. Some Linux distributions support USB class 2 Audio, does Ubuntu? Secondly What are you using to get bit-perfect audio playback through an outboard DAC. I plug mine in and it appears in the list when I run aplay -l but if I actually try to use it I get an error. I think it is the player I am using that is the problem not the DAC or Linux itself.
Now I know why so many people who use their computers mostly for entertainment purposes pick Apple computers. From what I have read the Apple OS nativly supports all this making most everything audio or video a simple plug and play option.

USB 'class 2 audio' is a subset of USB 2.0. Its only neded to play high sample rate files which are too big for the bandwidth of USB 1.1 (higher than 96kHz sample rate).

DACs dont exist by themeselves, you need the sound card/chip to be supported.

MacOSX isnt a magic bullet, and in almost any given industry/use there are more windows users tha OSX users.....and if there are no drivers for the device with OSX you are out of luck.