On the Q+A page, it does say that data transfer is not available, only charging.
What I intend to do (i think) is use a dc-powered usb hub (that provides bus power to devices), and hook that to the XPAL. From there, hook the dac + drive to the hub. I dont remember if the mini pc (hp 2133 in my case) has bus power to its usb port, but it may not matter.