My Mobo is Asus P7P55D-E with latest BIOS Version 1101
Please see my step:-
1.Crossfire EAH5670 enabling, and work properly until change new sound card SB X-FI.
2.unintall SB Audigy sound driver and others software SB Audigy related it require restart OS.
3.Restart Windows 7 and shutdown.
4.install new SB X-Fi PCI-express sound card
5.start windows 7 without install Sound Driver.
6.open CCC crossfire EAH5670 disable with no menu option "CrossfireX" graphic information show 2nd card disable adaptor .
7.install sound driver but Crossfire still disable.
Hmm I have an Asus P7P55D Pro. Not sure what the difference is having the non pro version. I know the "-e" means you have USB 3.0, but that only works when you have free PCIe lanes.
In my set up, I'm running two 5850s in 8x/8x in the top two 16xPCIe lanes - they're separated by 2 1xPCIe lanes. I have my AuzenTech Bravura 7.1 card in the second 1x lane. I then have a GT 240 in the bottom most 16xPCIe lane, which runs through the south bridge at 4x - I think you probably don't have this one.
Anyway so my advice is to make sure the sound card is in a 1x slot.
I believe that it is a limitation of your board and the pci-e controller on the cpu. 1156 employs a mcm design and it is well known that the cpu only has 16 pci-e lanes. Beyond that there isn't much I can do to help you. So you may have to go with out corssfire or the audio card. The on board audio is good enough these days for most users while this is for the audiophiles.