Did you disable the motherboard's on-board audio? in the BIOS.
Did you completely remove the Creative Recon3D software, before installing the newer Creative SBX software?
Might consider getting the DT880 Pro 250-Ohm headphones, more "balanced" sound then the DT990 and 250-Ohm headphone are a little easier for the SB-ZxR to drive.
Used DT880s start at $156.50
I did not disable to the onboard audio but I have never installed the drivers for it
I should have specified that I did a new pc build entirely and there was fresh windows install
I have looked at the 880s but what drew me towards the 990s was mad lust's review. At least what I pulled from it was that it was a fun headphone, still having bass and highs, while still maintaining directional accuracy.