Stray Peak

Forgetting all about the "why" for a moment, if it's only peaking (and not clipping) at track level and not at the master, then you have nothing to worry about in a floating point system.
The only time sound will be degraded is if you clip your converters.

So, you've got some fx on the track, right? EQ, Compression maybe? You say a limiter. I have found sometimes that I'll clip a frequency. Most of the moment is well below the clipping point, but maybe at one frequency I go over the top. Is that possible? So maybe a little fret rattle from a firm attack which the compressor lets through because of the attack setting?
 
I'm just WAGing here.

gswtiz, it looks like you're correct.  I turned off each module in ProChannel one at a time, turning off the gate dropped it to 0dB; but turning off Concrete Limiter with the gate still on dropped it to -1.8dB.  I suspect you're right that it's the attack in this location.  I'm not changing anything, but it makes me feel better to understand it.
 
Jeff, your approach is very intriguing, but I'll admit it's way over my head.  I'm more on the artist side of things.  Still appreciate it though -- always nice to learn how much more that can be accomplished.

M_Glenn_M
.... or also automation

+2.98768574768696857474636769

MorganT > Jeff is talking about using other Apps to make changes to the waves off-line and then to mix in Sonar.
 
Advantages include you getting processed (kinda like normalized but more specific -- in other words, the tracks might have a standard RMS level but not be using every available bit at the loudest moment). You can apply specific EQ and compression on specific wave cycles or transients. You can change the amplitude of certain waves by reducing the amount of different portions of the wave to make the adjustments as transparent as possible and as true to the original as can be achieved.
 
You can then apply all the FX and make all the adjustments and render a new wave file. The amount of processing required is some what irrelevant since it is the only work being done at the time. Then you render the new wave form.
 
Once you have rendered new wave forms for each track with a similar RMS level you can mix the remaining tracks more easily. Because all the tracks are 'gain-staged' or 'processed' or 'normalized' (all these have more specific meanings but I'm using them here anyway). In general, you know have minimally compressed tracks carefully adjusted to each have the same RMS levels.
 
http://www.gearslutz.com/board/mastering-forum/173236-what-difference-between-rms-peak.html
RMS is effectively an average of peaks over time.
 
Some people swear by staging RMS levels across various tracks before mixing the tracks.
http://www.kvraudio.com/forum/viewtopic.php?t=135884
 
In a lot of ways, this pre-processing is an effort to make the mixing easier. It might really help. Obviously, Jeff and others are sold. I have spent time watching RMS Levels on tracks as I mix. It's interesting info to work with and it does seem to help me get to a better mix faster, but I don't do off-line rendering in order to get the job done myself. I just send the tracks to RMS meters pre and post to get a view of what I'm doing to them all. It works pretty well if you don't have too many tracks.
 
One of the risks of pre-processing is over-processing the tracks. In my opinion, an example of over-processing a track is making a final mix at one level of compression and then deciding to make the whole track quieter for the CD. Worst would be to re-expand the compressed track!! why not double back and bounce the track with less compression to get a different RMS level on the final mix??
 
This is probably way more info than you wanted, but they are my thoughts regarding Jeff's comments (which are great comments btw). Jeff is pointing you to a really super great lesson in mixing. He is telling you how he does it which is with other software outside of Sonar. It is not a requirement to use something outside of Sonar to use the mixing technique. So, check out his lesson. Play around with RMS on the various tracks you are mixing. See if it doesn't help you get a better mix faster.