57Gregy
"The red" is still -6 dB. You shouldn't get distortion until you reach 0 dB.
Or not?

See, this is why I get lost. -6 dB and -6 dBSF are very different levels of volume. That's the point of my question. Aren't the main meters supposed to output in dBSF level?
 

Dreamer
What are they? My understanding is that dB is used for analog audio and dBFS is used in digital hardware/software audio. Why are Sonar meters described as VU, (an anolog standard)? Are they VU meters with three different flavors, (rms, peak and peak+rms)? Why aren't they dBFS level meters? Every time there's a subject on volume here in this forum referring to Sonar, I keep seeing descriptions in dB. Even in Sonar's help program volume is described in dB. I assumed all DAW programs are digital not analog. So again I ask, (I am very confused), what are they? There is nothing I could find anywhere as to what they are. Isn't the level output reading supposed to be dBFS? Even the measurement range selection for the meters is in dB. Please excuse my dumminess...I'm just so confused.

Ok... (cracks knuckles) let's take a shot:
Firstly, this article in the  TapeOp website http://tapeop.com/tutorials/54/meters/  has excellent perspective about the  behavior of VU meters and the need for other types of metering. 
 
Backward compatibility is reasonably possible to emulate, and there are a variety of plugins that attempt to mimic the mechanical ballistics and behavior of VU meters in the software.  As noted in the article, there are assumptions about the true peaks that are inherent in the mechanical ballistics that make it unsuitable for really keeping the reins on your musical compositions. 
 
In every DAW the meters are a dBFS scale.  The movement of the meters' lights/LED's, or green/yellow/red area fills can be coded to be true peak, RMS, temporary peak indicating, long-term integration, the combo plate with fries, or anything else the coders can make for you.  It has been a long time since I've used Sonar 8.5, so I don't recall how many metering behaviors were available in that release. 
 
Once your tracks are summed to the master output, then you're getting to the point where the calibration of the dBFS to the actual electrical levels of the D/A converter and the input sensitivity of the amp/speakers, and the dB SPL level in the air at your listening position begin to matter a great deal. 
 
In my studio, I've calibrated a -18dBFS level mono 1kHz sine wave output to be 80dB SPL at my listening position. That -18dBFS was calibrated on the input to be +4dBu.  In between, I can have a party with levels all over the place. 
 
I hope this helps you on your way.  Check out my articles for more detail.

Awesome Gary! But you're way above my pay grade, (I'm at the flux capacitor level...LOL). Good info and interesting write -up. I think I'm getting a little closer to understanding.
 
The image I included is of my main meters. I normally set them to peak+rms, (Sonar 8.5 only gives three options). If it is a dB FS scale then the the graphical display implies that anything above -7 is hot, (I generally float my mix between -7 and let my peaks tap -3). And what I'm reading around the www is that one should try to stay somewhere between -14 and -20 on a final mix. Is this right or wrong?

Awesome Gary! But you're way above my pay grade, (I'm at the flux capacitor level...LOL). Good info and interesting write -up. I think I'm getting a little closer to understanding.

The image I included is of my main meters. I normally set them to peak+rms, (Sonar 8.5 only gives three options). If it is a dB FS scale then the the graphical display implies that anything above -7 is hot, (I generally float my mix between -7 and let my peaks tap -3). And what I'm reading around the www is that one should try to stay somewhere between -14 and -20 on a final mix. Is this right or wrong?

My 0.02c. Peaks up to -0.1 are OK at mastering stage. Best to leave a few dB if sending off to mastering.
I've found RMS from -12 to -14 dBFS gives a reasonably loud mix without restarting the loudness wars!
I think there are different ways of measuring RMS (e.g. different K-metering standards, LKRS/LUFS) that take into account human hearing. I believe Sonar uses standard unweighted RMS.
 
dB is a relative measure. It compares the RMS of two signals. dBFS compares to full-scale. Two signals can differ by 5dB (say), or a signal can have a level of -3dBFS. See here for a little more info.
 
Cheers, Peter.

.

mister happy.....Yes, SONAR's meter's describe Full Scale units in decibel ratios: dBFS (not "SF")...
.....Give that a couple years to sink in, but in the mean time consider that you did not get the answer you wanted to your question because the question was not coherent as it was stated. Good luck.

 
Thanks Mister Happy. Actually I did get some good answers, (which includes yours). And thanks for correcting that transcription, (SF to FS).

The meters that Sonar uses are absolute. What they read is dead on accurate. VU meters are approximations.They have little in common with the meters in Sonar. Where some users get into trouble is adjusting the level being recorded using the track meters and the track fader or gain control while recording. Those meters need to be left at unity. All adjustments to level must come from the source. After recording then one can use the gain and fader to adjust level going to a bus. 
 
The reason for this is Sonar can not meter the incoming signal before it hits the AD converter. Leaving the meters at unity gives an accurate reading when recording. One can set up the record meters to any scale and change the ballistics to what ever value one wants. The playback meters can be set to a different scale and ballistic.  
 
I leave them at their default. 

Thanks John. Although I know what the track meters are I'm not sure of what you mean by "track fader or gain". Is that the volume and trim parameter?