OK I just downloaded and installed the free giveaway version of Home Studio and did offline activation. 
So I didn't have to uninstall SPlat. 
How it works;
You go to the help menu and there is a Offline activation send. Click that and save it to your download folder. 
This creates a .crq file with a number. 
Copy this and open your My Account page and open the Offline activation tab.
Enter the code and it will open a dialog to download the response code to your download folder. 
This shows as a file which will say - cactus music Sonar Home Studio Activation Request. dat  
Open Help again and select the Activation Response and it will let you browse to your download folder and select the dat file. Done. 
The Offline activation option will now disappear from the help menu.  
 
So the files you are looking for are in your download folder. 
 
I see that I had backed up these files to my Sonar serial number file I made for Splat. 
I will wait until tomorrow to try and see what happens if I un install / re install Home Studio and use these codes to authorize. 
 
 

The process of offline activation is clear. What is not clear is whether by using CCC to install and activate instead of doing an offline activation, there is anything that can be stored off your current computer that will allow you to reactivate in the event of a crash and repair. I would be greatly surprised if you could not activate a program on the same computer after an uninstall using the same offline activation file. That file is linked to that computer and (at least while stored on another computer) does not change. I presume that you would not only be able to use that offline activation file again on the same computer, but that a simple copy of the file using windows copy would work just as well. The issue matters because if people are installing and activating by CCC and a similar file or other token is not stored in a transferable format, then they may be able to move the CCC installer files to a backup, but they will not be able to activate the software after moving it back to the original computer after uninstallation or crash unless they can contact the activation server on the net. In that case, obtaining an offline activation file by the method described in your post and in the documentation would be necessary in order to do an offline activation of the software. Simply having the CCC downloaded files from backup would not be enough to assure your ability to do a reinstallation and activation.

At this stage Cakewalks servers are required to register (activate) Sonar, whether it be online via the CCC or the offline method.

The .crq file obtained in the offline process is good for that activation on that computer. I think it is also time limited. There must be some lock out method seeing as we all want and Noel has promised that if the servers go down we’ll have a permanent authorisation method that doesn’t require an online aspect.

Perhaps they’ll revert to the authorisation, method used for X3 and earlier. Where you enter your serial number and a generated registration code which is good for reinstallation forever more. If you go to your account you’ll see that X3 or earlier not only list a Serial number received at time of purchase but also a Registration number which is available through your account. Subsequent installations on the same or different computers, use the same 2 sets of numbers/characters.

I think Mike is correct in how this works and how they will have to fix it. It will involve changing the coding to remove the currant system and replace it with the old system. Just giving us a code is not the answer because I'm pretty sure it is a timed out system as Mike has said. I might try it as all I'd have to do is completely remove my free copy of Home Studio and then see if a re install would work using the same crq file. We already teted this on different computers and found out it's a no go, but havn't tested on using the same machine. 
A huge and most likely danger is you get a W10 update and bingo, you computer ID is now changed. 
 
So the only thing that will save us is the Bakers cook up one last release of Splat with using the old system with 2 numbers. Either that or a Dongle :? 
 
I think they are delaying this because Sonar is worth more money in it currant state. The release of an open activation would be a sign to me that Sonar is truly dead and never to rise again. 

slartabartfast
A related issue, assuming you have secured an offline activation file for your installation: How much can be changed on the originally activated machine without requiring another activation request. I am assuming that the change of a hard drive alone would not invalidate the original activation, but does anyone know?

 
From what I've seen I'm pretty sure the hard drive is the ONLY thing that invalidates the activation.
 
I've got a backup PC system, exactly the same spec, but obviously the CPU Serial No, Motherboard/BIOS Serial No, MAC addresses are all different. The Windows product key is also different.
 
I tried cloning my existing drive without cloning the hard disk serial number, and installed it in my backup PC - I needed to re-authorise.
 
Cloning it again, but telling it to also clone the hard disk serial number worked fined without authorisation.
 

msmcleod
From what I've seen I'm pretty sure the hard drive is the ONLY thing that invalidates the activation.

 
If you look at the Rapture Pro log file you will see (at least in earlier versions) it logs that it phones home regularly.
http://forum.cakewalk.com/Is-Rapture-Pro-Calling-Home-m3235518.aspx
 
So I do wonder after a period of time if these products deactivate themselves if the server is unavailable. Many people have or had the issue of software reverting to demo mode.

Cactus Music
...So the only thing that will save us is the Bakers cook up one last release of Splat with using the old system with 2 numbers. Either that or a Dongle :?

A dongle makes little sense.  Asking users (many of whom are anti-dongle) to go out and buy a dongle for software that's stopped development, well, would be like a final hard slap in the face.  Except maybe for a handful of users who already own a dongle, very, very few would bother.  Then there's the software maintenance that will never come...
 
I think your first idea (another release of sPlat - or maybe a patch - enabling the serial # activation) is really the only way they can go. 

Won't happen, developing a dongle method of authentication will cost them $$$, which they will not spend.