Hello all. I am having a recurring issue with the Audio Engine stopping and emitting a continuous buzz. This most often happens when I add a VST instrument to a project. It is not limited to a specific VST and doesn't happen every time one is added. I hear a loud click, the continuous buzz starts and a message appears saying the Audio Engine has stopped. As soon as I click on the Audio Engine icon, the buzz stops and all continues normally.
 
I am at the stage where I turn the volume of my audio interface down before adding a new VST instrument because there were times when I was mixing at a fairly high volume level and almost blew out my eardrums (and the speakers) with the click and buzz. I have tried changing as many settings as I can think of that might make a difference and have updated to the most recent firmware on my NI Komplete 6 audio interface but nothing seems to make a difference. Any and all assistance would be greatly appreciated. 

I have audio engine drop outs too, I do not know why.  I have just always assumed it was related to my audio interface, which is a Focusrite Saffire Pro 14 (maybe the ASIO driver, maybe my latency and buffer sizes.)  These dropouts can occur when adding something, like with your case, or when I stop in the middle of a song, and try to start in the middle of a lot of music happening at once.

In my experience, dropouts can be caused by a number of things...
1. competition for the interface
  a. Maybe netflix or some audio player that isn't Sonar that has a lock on the interface. For me this is often RME DigiCheck which has the interface locked to a different sample rate.
2. IO
  When there is too much work on the hard drives, dropouts can happen.
  a. Virus scanner
  b. Tons of large files like 96 kHz tracks with 50 takes in them. This often happens when I practice a tune on a loop just playing it again and again.
  c. windows updates / ngen work.
3. Processor over drive
  a. this one is the easiest to monitor and understand.
 
DPC Latency can also cause dropouts. Resplendant's DPC Latency Monitor is the best way to turn up these issues and discover the solution.

I have drop outs as well.  All my pupils are dilated.

Hi,
 
It sounds like you could have some hardware conflict (different driver is trying to do something what conflict with audio). Look for your drivers in manage computer and see if there are devices which are using the same IRQ.
 
But also try to increase buffer size in your audio driver settings and check if it will help.

When you experience an audio dropout, there's a Toast notification. If none of the above suggestions help, click on the Help button and go through each solution, one at a time, to fix the problem. I have yet to see a dropout problem that the Help menu didn't address.

Thank you all for your advice. In Preferences>Sync and Caching, I had Playback I/O and Record I/O set at 512. I changed both to 64 and, when adding multiple VST's, there have not been any audio dropouts, clicks or buzzes. So far, it looks like problem solved. Thank you all, once again. 

Thanks Ruckman65. I have never twiddled this value.
 
It never occurred to me to mess with it. Mine doesn't have caching enabled at all. Hmmmm.
 
File System

Enable Read Caching and Enable Write Caching. Choosing either of these options lets SONAR use the Windows disk cache while reading or writing audio data. SONAR will usually perform best with all caching disabled, which is the default setting. If your computer has an older IDE disk controller, or a disk controller that does not use DMA transfers, enabling caching may improve SONAR’s audio performance.

  
Note: Changes to these settings only take effect when you restart SONAR.

I/O Buffer Size. This value determines the buffer characteristics for transfers to and from the disk. Changing this value does not affect audio latency, but will affect the disk throughput for audio tracks. The default setting is 128. A higher value causes more audio to be buffered from the disk ahead of the playback cursor. If you are hearing consistent dropouts/clicks in your audio and if your project contains high bit depth (32/64 bit) or high sample rate audio (88.2K or higher), it may be indicative of a too small I/O buffer size. If so, try a higher I/O buffer size like 256 or 512. If audio problems persist, reset to 128 and try a different remedy.

Also, if you are playing a large file, and using maximum latency, a too-small I/O buffer size may cause dropouts or crashes. Try increasing the buffer size by blocks of 128.

I had the Audio Dropout, click, buzz problem rear its ugly head again today but only once. So, that is a vast improvement on the frequency it was previously happening at.   

Try turning off caching altogether. The help documentation suggests it's probably better with it turned off, and this is the default setting.
 
Cheers, Peter.