Until this is resolved turn your speakers off and use headphones OFF your ears.
 
What's your plug in list?  Does this happen when you try to change presets just in Spark, let's say?  Or does it happen when you change presets in any of the other plugins?
 
Would be nice to see a screen shot of your synth rack view which will show every softsynth and the presets being used for each one.

Maybe I should add that this is in ASIO mode, using the MOTU legacy driver, with a buffer setting of 256.

jackroller

11Dreams
Can you see your CPU performance? It seemed to be the deal with me. I had to fix the CPU Core balance. :)

I hadn't thought of that.  Which settings did you adjust?  I've got a 6-core CPU, I'm pretty sure I have the horsepower for this kind of thing.

Use Multiprocessing Engine - check
Plug-in Load Blancing - no check
Use MMCSS - check

MMCSS Thread Priority - 2
MMCSS Task Key - Pro Audio


 

under File Menu/Preferences/Configuration files... :) 
MMCSST thread priority is set to 2 in my case for my CPU. I don't know about your CPU, it may be set as default. I only had two options.  
I set the Enable set thread ideal processor to false. <-- this fixed the issues for me.

Thedoccal
Until this is resolved turn your speakers off and use headphones OFF your ears.

Way ahead of you.  :)

Thedoccal
What's your plug in list?  Does this happen when you try to change presets just in Spark, let's say?  Or does it happen when you change presets in any of the other plugins?
 
Would be nice to see a screen shot of your synth rack view which will show every softsynth and the presets being used for each one.

Screenshots are here:  http://imgur.com/a/jkwgE
 
I've got two keyboards, an Akai mpk61 and a Yamaha Clavinova.  SONAR's I/O is set to use MIDI channel 1 and 2 on each keyboard, and Spark is set to the mpk's pads on MIDI channel 10.  I just realized that the Analog Lab plugins are all set to MIDI omni by default.  If I set them to the correct channel it reverts back to MIDI omni when I change presets.

This morning when it happened I was changing presets in the fourth Analog Lab instance, from an SEM patch to the Matrix-12 patch shown.  Wasn't touching the keys, transport was stopped, click on the gui - BOOM!

I just looked at your screen shoots. do you have images in the background in Sonar? That could be an issues.
 
If this was me, I would start by setting my project to 16 bit. reboot my system and then try running the project.
Buy I would create a CWB file of my project so I could go backwards to where I was before experimenting...
If the problem was 24 bit.
Or make a back up file and slowly remove parts of your project that you may thing could be the issues...
 
Round and a round but I get caught up and get lost in finding the problem and the fix... lol
 

I think my post was eaten by the forum software.

jackroller
I think my post was eaten by the forum software.

maybe it's your hair.. ;) UFO Hair...
<
<
<

Are you saying the aliens are trying to communicate with me?

Can a moderator restore my post or do I need to redo it?
 

jackroller
Are you saying the aliens are trying to communicate with me?

Can a moderator restore my post or do I need to redo it?
 

What's wrong with your post?  it looks ok to me...  but you can fix your posts. Mods. can as well I think?
 
BTW, the Aliens are there.. you just have to listen for them... My Drummer is into all that... it's a cool concept...
 
Have a goodone! :)
 

Restored your post.
 
This is a most peculiar set of symptoms. The pop is almost certainly being generated within the plugin.
 
Does it still occur when the plugin's volume control is turned down, or when the plugin is bypassed?
 
Does it occur if you mute the master bus, as opposed to turning it way down? Some plugins have been known to generate bursts of ridiculously high levels, like +99 dB, that might remain audible even with the master fader down.
 
Are you sure the plugin is routed through your master bus, and you haven't inadvertently sent it directly to the hardware outs? With SONAR's master bus muted, SONAR is not sending audio data to the driver. If the synth is properly routed and SONAR's master bus muted it's guaranteed there will be no sound from SONAR. It would have to be another process injecting audio into the output buffers.