I'm having trouble inserting Altiverb 7 XL into a surround bus.  Rather than a single surround instance of Altiverb, I end up with Sonar's SurroundBridge and three stereo instances of Altiverb, thereby preventing access to Altiverb's surround capabilities.

The problem, I suspect, stems from Altiverb and Sonar both trying to be "smart" regarding channel I/O.  That is, Sonar automatically launches SurroundBridge when it detects a stereo plugin being inserted into a surround bus, while Altiverb XL launches as a stereo plugin by default, only enabling surround I/O after analyzing the host environment.  [There isn't a hardwired, six-channel version of Altiverb, unfortunately.]  Consequently, Sonar sees Altiverb as a stereo plugin and wraps three instances of it in SurroundBridge, where the plugin is forever encapsulated in stereo mode.

Hopefully, there's a workaround?  A secret INI setting, perhaps?

Any assistance is appreciated.

Have you already looked through these links?
 
https://www.cakewalk.com/Documentation?product=SONAR%20X3&language=3&help=SurroundMixing.15.html
 
 

I'm afraid so.  All of those articles introduce SurroundBridge and explain how it works with stereo and mono effects but without suggesting a way to defeat it.
 
Ideally, SurroundBridge would be optional or have an exception list whereby certain plugins will not automatically instantiate it when inserted into a surround bus.

This may be a wild goose chase, but I noticed when I downloaded SPlat yesterday that the local documentation had been updated on 9/30/2016. It may be more up-to-date than those X3 docs I linked to.
 
https://www.cakewalk.com/My-Account/Product/CSPT100?connectedProductId=195
 

Maybe I'm being dense here, but I can't find those docs.  I remember downloading the documentation update with the 2016.09 Sonar update, but can't find it on my hard drive.  It's a PDF, no?
 
They should really put a link to the local documentation in Sonar's Help menu.

No, it's not a PDF. If you use Command Center, it should be the last entry under Sonar Platinum. If it's green, then you should be up to date. I would probably download it again from "My Account," for good measure, unless a 600 MB download is a burden for you. The download is an EXE file you will need to install.

Yeah, I have it, but assumed Command Center took care of the installation.  So, I need to find an .EXE and run it?  Grrr....

Resort Records
Yeah, I have it, but assumed Command Center took care of the installation.  So, I need to find an .EXE and run it?  Grrr....

Only if you manually download it from your Cakewalk account.

Okay, I finally found the documentation:
 
C:\Program Files\Cakewalk\SONAR Platinum\SONAR Reference Guide.pdf
 
Not sure why Windows Explorer couldn't turn this up before, but it's there now and, I'm sorry to say, has few, if any, modifications to the surround topics.
 
But thank you for the recommendation.  It was definitely worth a look.

Resort Records
Okay, I finally found the documentation:
 
C:\Program Files\Cakewalk\SONAR Platinum\SONAR Reference Guide.pdf
 
Not sure why Windows Explorer couldn't turn this up before, but it's there now and, I'm sorry to say, has few, if any, modifications to the surround topics.
 
But thank you for the recommendation.  It was definitely worth a look.

There's no way that PDF is 600 MB. I don't know what all is included in the Local docs, but it's more than a PDF. I seem to recall some tutorials being included, but I'm not 100% on that.