Mastering plug-in / software

Ozone's your best bet.

I second Ozone 5 with the new Groove 3 tutorial on it.

If you on a budget, and your songs are not going to a professional medium (radio, Tv, national CD release) I think you can get fine results with the included tools in X1E.  Might want to find a Limiter or buy the new cakewalk one to crank the loudness.  Just my opinion.

Unanimous for Ozone so far!

When I mix down to a WAV file using the X1E tools  all my spatial resolution seems to get pretty tunnel-like.  Suggestions?  (Although I'll probably end up getting Ozone anyway...)  

I bought Ozone 4. Shortly, afterward the nice folks sent me an e-mail that I could bump up to Ozone 5 for free. So, I bumped up to 5. I really like 5 a lot, but since I got 5 Cakewalk came out with more ProChannel modules. I was in the middle of a couple of projects ready for mastering so I decided to do a test. Could I get equal or better results using the Cakewalk plugs as opposed to Ozone. I did two masters of each track. One with Ozone, one with Cake tools. I never changed the mixes. Just the mastering tools. The clients, surprizingly, chose the masters with Cake plugs. I know this sounds like a commercial for Cake. LOL! I was surprised myself at the results. It just reinforced to me that Sonar and a few of their purchased plugins are well capable of delivering pro grade mastering results. It has taken many years for me to get comfortable with mastering tracks, but now with these tools I enjoy the process so much more. And my knuckles stopped turning white!!!
BTW, I still use Ozone and it is dead on easy to use. For inexperienced mastering I would recommend Ozone, hands down. If you are a little more experienced and willing to try it, the Cake plugs will do a nice job for you!

If you're struggling a little in the Mastering department and need some guidance and more information then go over to the iZotope website and download the iZotope Mastering Guide.

Its one of the most informative, comprehensive and well written documents on the subject. Read it, study it again and again. You'll probably find that you'll get a lot more mileage out of SONAR's tools before you need to plop down any more money.

When you're ready to do so go for oZone 5 or the T-Racks Mastering bundle from IK Multimedia. There's a host of plugins but until you've explored SONAR's tools and find you need more - well you don't need more. many users even say that you don't need more than those tools within SONAR and that you can master perfectly adequately with only them.

Many of us had iZotope's oZone long before SONAR came with better tools so we established our workflows around those external 3rd part tools but there's no such thing as an absolute way. There's always room for more knowledge and adaptations to workflow brought about by using other tools.

(But I'm gonna start with Izotope's mastering guide to try making up some of the gaps!)

Thumbs up on the Ozone Mastering Guide! Even if you choose not to buy Ozone, that guide is invaluable when it comes to learning what mastering is all about. It is very concise but simple to understand. Just that download alone is worth going over to the Ozone site!