The X Station uses USB 1.1 - not 2.0.
This will not be updated on the X Station since there is no need. With the latest drivers, you can achieve a minimum input latency of 1ms and an output of 2ms.
For 2 in 2 out audio plus MIDI, it is not necessary to use a higher bandwidth interface since there is no extra data that needs to be transmitted. This does not mean the X Station is not compatible with USB 2.0 ports - you can run it from any USB port, 1.1 or 2.0.