z77 Extreme 4 - USB 2.0 problems with Audioengine D1 DAC

[A_Man_Eating_Duck]

Hi,

I've been having a rather odd issue with trying to use my Audioengine D1 with my my ASRock z77 Extreme 4 motherboard. Whenever I try and use the D1 with a 1m cable connected to a USB2.0 port (front or back) it will no detect correctly (shows as a unknown device). If I plug the D1 with the same cable in to a USB3.0 port the unit is detected and works fine.

Things I have tested;

• Plugged D1 with the same 1m cable in to USB2.0 port on a Dell E4300 laptop - The D1 is detected correctly and works fine.
• Plugged D1 with the same 1m cable in to any USB2.0 port on the ASRock z77 Extreme 4 - The D1 is detected as a unknown device and doesn't work.
• Plugged D1 with the same 1m cable in to ASMedia ASM1042 USB3.0 ports on the back panel of the ASRock z77 Extreme 4 - The D1 is detected correctly and works fine.
• Plugged D1 with the same 1m cable in to Intel z77 USB3.0 ports on the back panel of the ASRock z77 Extreme 4 - The D1 is detected correctly and works fine.

Does anyone have any ideas of what could be causing this weirdness?

Specs:
ASRock z77 Extreme 4 (BIOS v2.0).
Intel i7 3770.
MSI ATI 6950.
G.Skill 4 x 4GB Ram.
Crucial M4 128GB.
Corsair HX620.
Perc 5/i.
4 x 2TB samsung Green.
4 x 640GB WD Blues.
1GB Hitachi.
Audioengine D1 (USB\VID_1101&PID_0003&MI_00)

Windows 7 SP1 all updates.