The 256 settings you are seeing are likely a different set of buffer values.
Since you are using a laptop, I would suggest first seeing if the crackles go away when you either physically turn off the laptop's Wi-Fi adapter (it may have a switch or a function key), or go into Windows Device Manager and temporarily 'Disable' the Wi-Fi adapter there. Many folks find that if they turn off or disable their laptop Wi-Fi just prior to launching Sonar, then turn it back on or enable it when finished with Sonar, that Sonar works much better - without the crackles and such. Something with many drivers for laptop Wi-Fi adapters seems to mess with Sonar's ability to handle streaming audio. The Wi-Fi adapters/drivers spike DPC Latency and this is what messes with the audio, and why many folks turn their Wi-Fi adapters off or disable them.
Soooo, I suggest you try the above first. If that clears it up, then it is just something you will want to do just before using Sonar, and then turn it back on after finishing the Sonar session.
IF the above does not take care of your issues, then take a look at the following and please post back:
1. What Driver Mode is Sonar using? (Edit>Preferences>Audio>Playback and Recording)
2. What Sample Rate is Sonar set to use, and what are the various latency values reported by Sonar? (Edit>Preferences>Audio>Driver Settings - for both Sample Rate and latency values in Sonar)
3. What Sample Rate is the audio interface using?
4. Do the crackles go away if you hit the letter 'E' on your computer keyboard and then hit play in Sonar? (some effects are note meant to be used for tracking/recording, and 'E' toggles a bypass of all effects loaded in a project - hitting 'E' again will turn effects back on for the given project. IF the crackles go away after bypassing all effects, then one or more of the project's loaded effects are messing things up for you).
5. Are these crackles happening during recording/playback or in mixing? (when mixing, you will typically want your ASIO Buffer Size to be way higher than it is for recording. I use 1024 when mixing, and 128 when recording. The small size helps keep lag to a minimum during recording, and a large size helps effects have a big enough buffer to do their thing while mixing. You will typically change the ASIO Buffer Size from small to large or back to small again, depending on whether or not you are recording or mixing).
6. You are running Windows 7, so you can download and run DPC Latency Checker (it does not report accurate times in Windows 8 or 8.1), or you can download and run another freeware program called LatencMon. Both programs can help identify issues with a computer's ability to handle streaming audio applications, such as Sonar.
DPC Latency Checker is at:
http://www.thesycon.de/deu/latency_check.shtml And LatencyMon is at:
http://www.resplendence.com/latencymon Bob Bone