I have found an interesting workaround to an issue I am having. I described it here in a thread specific to the UFX, but it occurred to me this issue may apply to other interfaces.

http://forum.cakewalk.com...spx?m=2916781&fp=8

I have numerous problems that seem driver related with my UFX, mostly with FireWire but to a lesser extent with USB. I use ASIO drivers as recommended by RME. I get crackles, pops, dropout, sluggish behavior while arming tracks or changing preferences, etc. I noticed that after trying some other drivers (which were worse) and then reverting to ASIO suddenly the problems were gone. After some experimenting I discovered that the act of running the sounds card profiler, which happens anytime you switch to a non-ASIO driver, fixes the problem for the the session. After restarting Sonar the problem comes back and is again fixable. This is 100% repeatable.

ASIO drivers are not supposed to need the profiler, and in fact switching to ASIO does not trigger the profiler. So I am not sure what is happening. It seems like there is some initial "miscommunication" between the UFX and Sonar, and that this is corrected once Sonar pings the UFX during the profiling process.

I wonder if this approach could help other folks who have experienced poor performance. I am also very curious if anyone has ideas why this is happening. I will follow up with tech support at both CW and RME, but thought some folks here may have helpful insights.

Running the profiler communicates with the device using the WDM kernel streaming interface and tries to set the driver into various modes for different sample rates and bit depths. It also tries to query the optimal buffer size. 
Drivers typically share a common core for ASIO and WDM mode and many drivers even simultaneously allow access to the driver in different modes. If running the profiler is changing behavior in ASIO my guess is that there is something within the driver that is uninitialized or getting out of sync when running in ASIO mode leading to the behavior you are seeing. If the recipe is repeatable on different systems I would suggest first getting in touch with RME so they can troubleshoot it with you. From SONAR's point of view it would be difficult to know why the driver is exhibiting this problem since its driver specific. You can ask RME to get in touch with me if they need any assistance from the host side of things.

Noel,

Thanks for the reply. I will pass this info on to RME. One odd thing from the Sonar end is that I don't have this problem with 8.5. Not sure if that changes your assessment. Hopefully between you and Matthias over at RME you can work this out.

Cheers,

David

And can you tell me the best way RME can reach you directly? Feel fee to send me a pm. Thanks again.

I'm sure that RME folks know Noël very well. Just let them know to get I touch with Noël.