This was posted on the Cakewalk blog, and posted by Cakewalk on Facebook.
http://blog.cakewalk.com/an-audio-journey-through-the-signal-path-in-sonar-x1/ "Mastering." I believe there are two types. A. Professional true audio mastering. B. What I have affectionately been calling, "home grown, or home brew," mastering.
The differences are beyond the scope of the thread... but, "if a mastering plug is used" than you should have the Pro-Channel Post FX bin, and use the Concrete Limiter last. IMHO, for home brew mastering, the Pro-Channel EQ is a great choice. Although, I've been using the LP64.
Now, let's put the mastering conversation aside for a second... The order of modules on the Pro-Channel changes depending on what the material is calling for. There is no, "one correct way." Read the Cakewalk blog post, know the audio journey through Sonar..