The backstory: With sample buffers below 256 samples, regardless of the interface I would often get the dreaded audio system motorboating where Sonar would lock up, not be stoppable from the Task Manager, and require a reboot to get working again. Recently, there was a thread here about latencies and I thought I would try using lower latencies again. The problem persisted. I just assumed that the V-Studio drivers were kinda old, that my projects were getting more complex, maybe I needed a faster processor, etc. 
 
Then I thought maybe some  Device Manager process was causing a problem (someone had mentioned improved performance by disabling the network card), so I started experimenting. Of course I had already disabled the Realtek High Definition Audio driver but there was also another audio device under Sound, Video, and Game Controllers called AMD High Definition Audio Device. It didn't have an option to disable, only uninstall, so I never messed with it.
 
The fix: In my computer's Device Manager under System Devices, there's an entry titled High Definition Audio Controller. I was able to disable it, and poof - the AMD High Definition Audio Device disappeared from Sound, Video, and Game Controllers. Since disabling this, Sonar has run flawlessly for two days straight on two different CPU-heavy projects with a 48 sample buffer!
 
A possibly related issue: It's been noted several times in these forums that the choice of graphics boards can have a huge impact on Sonar's performance. Maybe it's not the graphics card itself, but the audio driver installed with a board. I'm pretty sure nVidia boards install some kind of audio driver as well.
 
I am one effing happy camper right now. 48 samples!! If anyone looks into this on their system, please report back and let us know if it helps. I can't believe the difference.
 
 

I disable the nvidia audio driver myself. I believe it's what drives the audio via a HDMI connection so you can get sound through the speakers of your connected TV set.

Do you have to disable it under System Devices or could you disable under Sound, Video, and Game Controllers? Did you notice a performance hit when it was enabled? I'm curious whether this is AMD-specific or has broader implications.

Will give this a try and see what happens thanks for the heads up.

Anderton
...but there was also another audio device under Sound, Video, and Game Controllers called AMD High Definition Audio Device. It didn't have an option to disable, only uninstall, so I never messed with it.
 
The fix: In my computer's Device Manager under System Devices, there's an entry titled High Definition Audio Controller. I was able to disable it, and poof - the AMD High Definition Audio Device disappeared from Sound, Video, and Game Controllers.

Thanks for this !
 
I also have the AMD HDA-device.  However, I can disable it, and just did as I don't need it.
I don't have it appearing under System Devices.
 
 

Hmmm, I haven't had issues running at low latency in general (unless I'm running lots of high CPU plugs) but I disabled the "High Definition Audio Device" and I'll run some tests on some of those high CPU projects to see if it makes a performance difference on my system.  I have an AMD ATI Radeon 4300/4500 series video card.
 
John

Wow a useable 48 sample buffer size  , that is fantastic news . I need to check my system out ...
 
thanks for the heads up 
 
Kenny

Anderton
Do you have to disable it under System Devices or could you disable under Sound, Video, and Game Controllers? Did you notice a performance hit when it was enabled? I'm curious whether this is AMD-specific or has broader implications.

 
Nvidia has an option in their control panel to turn off Audio.  I've never had a problem with it interfering with Sonar but I turn it off anyway since I don't use it.
 
Dan

Hope it works as well for others as it has for me. Of course I assume this is not a universal answer but it would be interesting which, if any, setups benefit from this change. I can't believe the difference it made in mine.

I found by buying a Focusrite Saffire Pro 14 made my (music making) life better than it was. Your solution was a bit cheaper though!

Grum.