I recorded some vocal tracks this morning. No problems. Previewed some other in-progress stuff. Again, no problem. Now, all of a sudden, Sonar is clipping all over the place--the entire mix on any song is terribly distorted.
 
If I shut off my audio interface and turn it back on, the problem goes away. However, as the song plays it steadily begins picking up more and more static and noise, until it reaches a point where it's no longer distinguishable as music.
 
The only thing new that I've added to the setup is Addictive Drums 2. However, why would this make old mixes behave this way?

The clipping only started after you added an instance or AD2?
 
You may want to look at those tracks then and what is being outputted/recieved by it.
 
If that is not the case... what interface are you using?

Also if it is AD2... just multiselect the audio outputs tracks, hold Ctrl and turn down the Gain (either the fader in the Track View/Track Pane or at the top of the Console strips).

Are you sure it's clipping distortion, or is it just that a lot of buffers are getting dropped (i.e. severe crackles)? Your description sounds more like the latter. Or are you actually seeing track/bus masters going over 0dB?
 
If it is a case of the crackles, you're either running too low a buffer, or something is suddenly inducing a lot of DPC latency (e.g. wireless networking enabled). Is the load balancing nicely across all CPU cores? Some plugins can really hit the first core hard.
 

It doesn't just happen with AD2, but with any project. It could be a single instrument playing Twinkle, Twinkle.
 
@brundlefly: It's not a decible problem. I'm beginning to suspect wireless networking as the culprit, although I don't know why that would affect Sonar. At any rate, the problem has suddenly disappeared after doing a reboot.
 
Since you brought it up, I can have my buffers set at 4096 and Sonar still gives me the ol' low buffer warning.

I've had a simular situation with adding a reverb to a project.
After some testing I'm starting to think an excess on 20.000 + frequencies is too much for Sonar or my soundcard.
A lower sample rate and higher buffers make it stay away longer.
Maybe you could filter out 20.000 hz and higher on masterbus and see if it goes away..

Wi-Fi adapters/drivers are NOTORIOUS for inexplicably jacking up DPC Latency, and many folks resolve this by turning off or disabling their Wi-Fi just before launching a Sonar session, then turning it back on or enabling again right after finishing the Sonar session.
 
Give that a shot and post back, please - there certainly may be other things happening, but the above is an easy place to start.
 
Bob Bone
 

I am going to go out on a limb here are suggest the possibility of a faulty sound output device.  As a quick, temporary test, are you able to switch to your on-board (or any other alternative) sound card and play a project you know would have made the clipping distortion manifest.  If your test project plays without distortion then, it might appear you might have a faulty sound output device.

Buffers is not a "fire and forget" thing. They can require adjustment, and can also be set too high as well as too low. They often have a sweet spot that is specific for the system and task.

Where is SONAR giving you a low buffer warning? Melodyne?

@mettelis: Yep. It's always Melodyne.
 
@promidi: Unfortunately, I only have the one interface (AKAI EIE Pro). The computer doesn't have a decent soundcard. And, the problem has went away with a reboot.
 
@The Bone: I'm going to take that advice to heart and start yanking that WIFI adapter. Perhaps one of these days, all this technology can get homogenized so as to avoid such problems.