I recently got the sonarx2a patch and have this odd problem. When I export my mixes to wav PCM they clip like crazy even though the levels arent peaking. There is no audible peaking in the session, only on the WAV mix. When I try and mix it down to a different kind of format like normal Wave, the peaking is gone but instead sounds like a really tight compression was slapped on the whole track and makes it sound wierd. I never had this problem with the first version of x2. Has anyone else had this experience? 

This is not the X-version forum, but the basics should be the same as in 8.5 and older.
I don't know what's he difference between PCM and ordinary wave, but I think most (??) use
Broadcast wav-format  when exporting.
You don't so easily hear clipping in session due to the floating point technique. You must look at the level meters, not trust your ears.
Do you route all tracks through Master Bus and use Master as the export source? If Master level shows around - 0.3 dB you're loud enough. So you're sure it's clipping, not otherwise distorted?

http://support.microsoft.com/kb/89879
 
PCM  "IS" a WAVE file, just one of the formats. Broadcast WAVE is just a timestamp format, it is still a WAVE file. 
 
There should be no difference when you export. You are simply hinting your master to hard. 
 
And I think most of us use the "WAVE"   option, broadcast wave is for film work. 
I don't own X2 but on my version of Sonar it defaults to "WAVE" ( wav. ) which is what you want. There is no PCM option even though that is really what you have. PCM is just a sub category that is standard, the other subcategories are obscure and not commonly used. 

Verify that all of your tracks are routed through the master bus. Mute the master bus. If the playback doesn't go silent, then some of your tracks are bypassing the master and going directly to the hardware outs. This can result in unexpected clipping.