To clear up a couple of things regarding USB:
There is no performance advantage connecting a USB-2 unit to a USB-3 port.
Prior to Intel Z series motherboards, literally *ALL* USB-3 ports were via 3rd-party controllers (USB-3 hadn't yet been integrated into the Intel chipset).
Many older USB devices have issues with 3rd-party USB controllers.
Liken the situation to using a non-TI chipset Firewire controller with a Firewire audio interface.
If you're running a fairly current Intel based machine, you've got Intel USB-3.
This greatly reduces the odds of incompatibility with USB-2 devices.
If you've got a USB audio interface that isn't being recognized (when connected to a USB port), that's sometimes caused by an impedance related issue. Try using a powered USB hub (even though it's typically not recommended) between the audio interface and computer's USB port. That will resolve the impedance issue, the audio interface will be recognized and work fine. In this scenario, I wouldn't connect anything else to the USB hub.