If you use a USB hub consider getting one that is Multi-TT (Multi-Transaction Translator).

I don't use one for my Fireface UC, that gets it's own dedicated port, but I do use it for everything else.

Single vs. Multi-TT hub comparison:
http://www.tomshardware.com/reviews/usb … y,677.html

Example:
http://www.amazon.com/Cables-Unlimited- … =pd_cp_e_0

Info:
http://en.wikipedia.org/wiki/USB_hub
To allow high-speed devices to operate in their fastest mode all hubs between the devices and the computer must be high speed. High-speed devices should fall back to full-speed when plugged in to a full-speed hub (or connected to an older full-speed computer port). While high-speed hubs support all device speeds, low and full-speed traffic is combined and segregated from high-speed traffic through a transaction translator. Each transaction translator segregates lower speed traffic into its own pool, essentially creating a virtual full-speed bus. Some designs use a single transaction translator, while other designs have multiple translators. Having multiple translators is only a significant benefit when connecting multiple high-bandwidth full-speed devices.[1]

It is an important consideration that in common language (and often product marketing) USB 2.0 is used as synonymous with high-speed. However, because the USB 2.0 specification, which introduced high-speed, incorporates and supersedes the USB 1.1 specification, any compliant full-speed or low-speed device is still a USB 2.0 device. Thus, not all USB 2.0 hubs operate at high-speed.