It's that Creative Lab doesn't want to support x64 ASIO. Some dedicated users have found a workaround however.
Download the latest x-fi drivers (the beta one, because Creative Labs has intentionaly removed two files so that the workaround doesn't work).
Unzip the driver manually.
Create a .bat file in the following folder you unziped:
SBDRIVER\DRIVERS\SBXF\
Enter these lines:
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ Ct20xspi.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ ct_oal.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CTAPO64.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ ctasio.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ ctdproxy.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CTEMUPIA.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CTMLFx64.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ ctosuser.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ ctppld.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ ctpxst64.exe %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CTtele64.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CTxfiBtn.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ Ctxfihlp.exe %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CTxfiReg.exe %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CTxfiSpi.exe %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ CtxfiSpk.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ devreg.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ enlocstr.exe %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ killapps.exe %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ piaproxy.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ regplib.exe %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ sfman32.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\amd64\ sfms32.dll %windir%\system32
copy /Y D:\Desktop\SBDRIVER\Drivers\SBXF\wdm\common\kill.i ni %windir%\system32
%windir%\system32\ctpxst64.exe
%windir%\system32\regsvr32.exe /s ctasio.dll
%windir%\system32\regsvr32.exe /s ctppld.dll
%windir%\system32\regsvr32.exe /s ctdproxy.dll
pause
Of course, you will have to replace the D:\DESKTOP\ by the location you put the unziped x-fi driver.
Save the file.
Run the .bat file as administrator.
Voilà, x-fi ASIO, x64 flavour.
Reference:
http://forums.creative.com/t5/Sound-...522787#M138625