Noel needs to clarify his fix.  Is it just for X1? or is it applicable to other versions?  Did X2 or X2a address the problem?  Is the fix for Windows 7 64 bit systems only or does it also apply to Windows 8 64 bit systems, and/or Vista 64 bit systems?
 
The registry hack that he posted is for an MAudio Fastrack Ultra registry entry, not a Sonar registry entry.   

Just installed the X2a update and the 6.1.9 Fast Track Ultra driver update and discovered that the ASIO option no longer works. When I change the driver mode to WDM/KS, it identifies my M-Audio hardware and proceeds accordingly.
 
I tried the registry fix to no avail.
 
One caveat is that the driver installer would only run in Windows 7 compatibility mode.
 
Any thoughts from The Collective?
 
ADVthanksANCE
 
-Jack (in South Austin)

And now that I have re-read the registry instructions, I'm not sure if I got it right or not.
The only entries in HKEY_LOCAL_MACHINE\SOFTWARE\ASIO\M-Audio Fast Track Ultra ASIO was a CLSID with some kind of hex address string. There were no device names in clear text.
 
Notice that the key I found did not include the 64-bit parenthetical expression.
 
Is this the big red flag waving at me to identify my install problem?
 
-Jack

...and the hits just keep on coming...
 
I just revisited the registry key entry and found the description text as described and changed it from M-Audio Fast Track Ultra ASIO (64-bit) to M-Audio FTU ASIO (64-bit), and now the ASIO devices appear in my 64-bit X2a application, but only the WDM are available in the 32-bit PE8.5.3.
 
Then, I visited the 32-bit command prompt window to discover that there is no Description element in the driver key of interest, so I added one with the title of M-Audio FTU ASIO and now I have ASIO working in both worlds.
 
I now know enough about RegEdit to be a real danger to my system, so I am going to stay away from there as much as possible. >8]
 
Hopefully, this will help someone else who runs into the same issue.
 
-Jack (who is both more confused and more operational than before)
 

I didn't have any issues.  The driver update installed in Windows 7 Home 64 bit and Windows 8 Pro 64 bit without having to use compatibility mode.  I did install it as "Run as Administrator" but I don't know if that was really needed.   I have X2a Producer 64 bit and as I previously noted both the Win 7 and Win 8 installations have no problem and immediately recognized the FastTrack Ultra 8R as ASIO and set it as the recording device when I started Sonar.
 
BTW, my name is Jack too.