My system

Win 7 sp1 x64
4GB Ram
AMD Phenom 9600 BE (TLB disabled of course!!)
**LSI 1394 OHCI Compliant Host Controller** Firewire controller! Take note this works with this firewire card but might work with others!
Fireface 400 (latest driver)

Cakewalk Sonar X1c

I was having some issues past months using FF400 with Sonar x1. My main issue was not having the ability of changing ASIO latency on the fly. Sonar would get stuck and playback controls would freeze. I read somewhere that this had something to do with the Audio driver and that sonar could not lock onto it. I recently reformatted the pc and did a fresh installation of everything this week, but still this problem occurred so i knew it wasn't a windows problem had to be a driver problem.

This got me fed up and i noticed that sometimes first playback would be silent and playback controls would not work. Stability of the ASIO driver seemed to be a bit temperamental and as we know in a studio environment we just don't want that. I just wanna do music and not be a pc tech

I was doing some research on a solution and I happened to stubble upon a solution from the social.technet.microsoft.com cant remember what exact link it was and what specific hardware it was talking about but I remember it had to do with something using the firewire controllers on win 7 and this has solved all my problems

Basically you use Legacy drivers for your firewire Controller its that simple. They are preinstalled in win 7. Let me show you through simple steps even with pics (with a relaxing background) for those less tech savy!

Goto device manager. (windows key then type device manager!)

check what firewire controller your fireface is connected too (I have two the VIA one is just a usb/firewire combo I use for extra usb slots)

[img align=c]http://img840.imageshack.us/img840/1783/part1ou.png[/img]

Right click on the firewire controller your fireface is hooked upto (the LSI one in my case) and press "Update Driver"

[img align=c]http://img38.imageshack.us/img38/3713/part2lw.png[/img]

click on browse my computer

[img align=c]http://img651.imageshack.us/img651/7322/part3u.png[/img]

click on let me pick from a list of device drivers on my comptuer

[img align=c]http://img525.imageshack.us/img525/9090/part4b.png[/img]

Select the 1394 OHCI Compliant Host Controller (legacy) <--- this should be preinstalled in windows 7 x64

[img align=c]http://img18.imageshack.us/img18/7717/part5j.png[/img]

Success

[img align=c]http://img510.imageshack.us/img510/8615/part6.png[/img]

Now restart your pc as the first time i tried this the fireface actually lost the connection with windows.

This has made the ASIO driver feel much more stable ive not had a single problem since i did this.
It works with the LSI controller but i suspect it might work with other firewire controllers too. Give it a try nothing to loose (Except maybe 5 min of your time)
I knew a brand like RME couldn't have been making dodgy drivers and look where the problem was not RME, not Windows, not Sonar but the firewire controller!!
No need to change your firewire card just try that might work for you as it did for me!!

Let me know if it actually helped you too especially with other branded firewire controllers!!