So its basically a mixamp, but for laptop or pc?
Yes, I usually plugged my aune via usb, so it bypass the on-board sound card. My laptop only got the crappy Realtek sound card, no optic output. The U3 come with optic dongle, so I can plug it to my Aune via optic out from laptop usb.
So the U3 is best with movie and gaming, not good for music?
So basically the U3 is "Mix-amp" that uses a USB connection (for a desktop or laptop)
The U3 will really have no effect on the "audio quality", when it's connected optically to the Aune T1.
For 2-channel audio, like music, all the U3 is doing is passing along the digital audio signal, to the Aune T1.
Try using the program Foobar2000, it's good for sending a audio signal, from a computer's the USB port (or a computer optical or coaxial port)
When using the U3 for surround sound for gaming and movies, the U3 will process the 6-channels (5.1) of digital audio
down to 2-channels of Dolby headphone surround sound, which is passed to the Aune T1, where the Aune T1 handles "audio quality", using it's own DAC and amp.