I assume your USB DAC is 96/24 capable (max). If I'm not mistaken, you need drivers to go any higher on Windows systems.
yes, we are testing the feature and will ask some user in China to help us test the new firmware cause there are so many kind of OS, and PC/Laptop, it will be better to fix most bugs before we release the formal firmware.
the USB DAC feature in X3 will support up to 192K/24B and need to install a driver in Win XP/7/8 and plug and play in MAC OS without any driver.
I use both Windows and Macintosh systems and I AM willing to help.