I’ve been using T-Racks suite for mastering  but picked up Slates fx-g plug and decided to use X2 for some mastering. My question: what’s your process for mastering with X2?  Do you mix down your finished song to a stereo WAV file then dump that file back into X2 and do your mastering?  Other suggestions?  Thanks

I picked up iZotope Ozone 5 and it is pretty cool, however sonar has all of the same tools, at the time I didn't know this. So if I would have taken the time to investigate the sonar plugs, i could have saved a few bucks. however there are some presets in the Ozone that are helpful, they at least get you started.

I mix down to a 24bit stereo track and, import into a new project to master with Ozone. works well for me. So I expect someone else to post telling me I am doing it wrong....

I'm no mastering expert, I know just enough about it to know I'm not good at it. That being said, I use the same method as Tracey, only using Ozone 4.

For my last session, I used the Sonitus multiband and the LP64 ultiband on the master bus, but they caused some glitched noises just at the playback of my tracks(I have not felt the need to increase the buffer latency for a mixing situation, because I have a powerful computer and the ressource processor was very low); the glitches have disapeared at the third playback without doing nothing(the mysteries of Sonar !!??)
Finally, I chose to leave the Sonitus multiband : it  tightened the dynamics and cleared the spectrum in a pleasant way and I achieve this result easier and faster than with the LP, but I lost a little stereo width in comparison with the no processed sound !
I think that Ozone 5 is more efficient because of its algorithms and the low deep end is better enhanced; I demoed it and I was very seduced by the way it boosted the sub and bass frequencies  :It "shimmered" my ears as we can listen in commercial productions and  Ozone 5 seem to be rather clear for the other frequencies ! For the Ozone 5 users, could you confirm ?

But it seems that Flux Alchemist would be the winner...

Does not Slates fx-g is convincing ? The other Slates plugs are said to be great for mastering purposes, no ?

Concerning the pro channel, I'm not really convinced by their compressors, nor their Console emulation ;;; they do the job in a mixing context, but they not "sublimate" the sound, imho, and the PC Eq should be efficient but personnaly, I can't work properly in such a little gui.

its all about your levels in mixing before you even take it to mastering.
remember that.
you shouldn't be clipping or in the red. save the boost for mastering not mixing.
the biggest mistake by beginner's is they abuse headroom on their mixes and once mastering starts 
they say "wha happun" ? 

You might check out this
 
http://forum.cakewalk.com/tm.aspx?m=2248173&high=Mastering
 
in particular the post from Bitflipper was most usefull for me.
 
meh

Once you've used a dedicated wave editing program like Wavelab it's hard to even consider Sonar for the task. It works but is missing way to many quick access tools, Example normalizing, an important task, Takes few seconds for Wavelab to scan and report your peak levels, RMS and averages. Try that with Sonar. Your working blind. 
If your not into forking over extra money I would be at least tempted to use Audacity which is free. Wavelab Elements is all you need and it is very affordable. I'm sure the other brands are comparable too, just never have used them myself.  

The plug ins should be shared with all your music software so you should have access to the plugs your using, I use a combo of all. 

I highly recommend using Wavelab for Mastering. For the price, it's great. It can handle a lot of the formatting your music needs, and now supports DDP. It also has great metering without additional cost. If their metering is not enough, seek out Flux/Ircam plug-ins. 

For technique, chuckebaby is correct, that many abuse the headroom. Finalizing the mix is an exercise in maximizing dynamics vs. musicality. You will not want to compress the mix too much, or maximize the volume. You should never need a limiter on the main output (ever) unless you are going for an effect. 

It's a tricky learning process, and I dare say there is not defacto method to mixing or mastering. This is what's great about this field of work. The magic. Each engineer has his/her own magic jelly beans to add, so don't expect your earlier masters to be grammy-stealing gems, although I think the Grammy awards are one of the biggest insults to music these days.