Wookiee - according to that thread, you should always do everything except and never do anything but. Unless you have a Commodore 64. But I have a Commodore 128, now what?
 
Rebel007 mentioned:
"There are several pages in the new .pdf that has just become available for download on this very subject. It gives good advice on what should be tweaked for optimum performance. There is a whole chapter on computer, software (read Sonar preferences) and audio device setup."
 
Anybody know what .pdf he's talking about?

I've had a similar experience with a fast track ultra.  One of the issues was with changing the usb ports.  I removed the old device from device manager using the show hidden devices option, but I noticed later that this did not remove the associated audio input and output ports from device manager.  I would first start by opening device manager and looking for ghosted outputs and deleting them one by one. 

Then, I would disable all HDMI audio outputs and other audio drivers in your system.  Make sure you have the latest drivers installed - they are being developed by avid now and are here  From experience, go into device manager and uninstall all the fast track components, starting with the audio inputs and outputs, then the Pro itself, then unplug the pro from your system.  Uninstall the current drivers from Add/Remove programs and restart your machine.  Install the new FTP drivers and plug in the interface.  
Lastly, rename the cakewalk aud.ini file in "C:\Users\<your username>\AppData\Roaming\Cakewalk\SONAR Platinum" and start platinum. This will force sonar to see only your FTP first, because all the other audio devices have been disabled.  You'll have to change settings in preferences again, but it's usually not a huge undertaking. 

rd2rk
Bitflipper - nope, nothing weird on any of the channels or busses. I listened to it for a bit thru headphones. It's weird, I can hear the guitar, and the drums, UNDER the distortion. Tomorrow I'm going to try a new project, just the one channel for guitar, take that from my pod, no (guitar or effects) plugins, and a channel for ezdrummer.

I don't know your interface - but are you using more than one mains stereo out from Sonar?
 
I had a few years ago an issue, since I have separate out for a dac and monitors and use analog out for headphones.
 
It turned out to be overs on analog outs, since interface had every out also routed to analog outs - so double signal means 6dB extra level. So using RME Totalmix correcting this routing, it all went fine.
 
Anything that rings a bell?