[Solved] several audio oddities about levels

(I've edited this post so that my full description of various problems appears below)

When I am mixing in SONAR X2 (audio is 24 bit 44.1 KHz) such that my master output spends most of its time between -6 dB and -3 dB only occasionally going higher without clipping and occasionally dipping lower, I find that upon exporting at 44.1KHz 16 bit with any particular dither, that the wav file I export is consistently far lower in volume when I meter it as an exported file.

For example, I can take a wav file, import it into SONAR X2, normalize it at 0, export it and load that export into Audacity that it plays back at a lower volume then what I heard in SONAR. Further more, if I normalize it again in Audacity, it adds considerable volume and then sounds to be as loud as it was when it was in SONAR. So my question is, what am I doing wrong to cause my exports to be at a decibel level much lower than I thought they were at when I mixed them down?
 
Thank you for your help.

But why is my rendered export way lower in volume than the project itself?

Allow me to expand on a description of this and other problems I am having.

I am having several audio problems in SONAR X2 that perplex me. First the relevant parts of my system.
I am running SONAR X2 Producer on a windows machine with ASIO drivers loaded for a PreSonus 16.4.2 ai digital mixer. The computer runs at 3.5 GHz and uses an i7 processor and has 16 GB of ram.
It is possible each of these problems are related?
 
Problem 1: all of the audio I tracks using this set up indicate that the wave files being recorded are at 32 bit 44.1 kHz. But I would prefer to record at 24 bit 44.1 kHz. The option to select bit depth for recording in SONAR preferences is grayed out at 24, I find nothing in PreSonus Capture or in the PreSonus Universal Control that allows me to alter bit depth. There is nothing in the system menu on the PreSonus 16.4.2 ai mixer that allows me any control over bit depth either. How do I set recording bit depth to 24?
 
Problem 2: In SONAR, the program works absolutely just fine without my having to assign the Master output to ANYTHING. In a current project, all tracks are assigned for output to a Bus (A thru F) and all buses (A thru F) are assigned to the Master output. However, the master output is NOT assigned to anything and yet the sound arrives back at stereo pair 1&2 of the PreSonus mixer with the "D))" switch engaged. I also get a warning when opening SONAR telling me, "The following tracks and buses are currently assigned to a silent hardware output. The items listed below will be silent in your project until their outputs are reassigned to an appropriate hardware output." and the Bus identified is "Master."
 
I have used the "H" key to examine all possible hidden tracks or buses. None are hidden, all tracks are assigned to one of the buses (A thru F) and all buses (A thru F) are assigned to the master output. The master output fader, though assigned to NONE as an output, still has the ability to raise and lower the overall volume of the mix and I hear the results as expected quite clearly through the PreSonus mixer. So for example, If I pull the Master fader down all the way to - inf, the project is silent; but if I place the Master fader up to unity gain, the mix sounds as I would expect it to and arrives at the PreSonus mixer at channels 1&2 linked as a stereo pair and engaging the input meters of the PreSonus as I would expect on channels 1 & 2. HOWEVER: If I assign the master bus fader to stereo pair 1&2, then I no longer receive the warning of a silent track or bus, but the output appears normal according to meter in SONAR and yet is way overdriven as it arrives at the PreSonus and pins the input meters on the PreSonus mixer strongly into the red. So I am confused as to how I get any sound with that Master fader unassigned but too much sound when it is assigned. Somehow assigning that fader's output causes the signal it sends to the PreSonus to be doubled (or more) when assigned and single when unassigned. Whereas it should be a single signal when assigned and silent when unassigned. What the hell is going on with THAT?
 
Problem 3: exporting audio from SONAR X2 results in erroneous levels. For example I can create a project with a single track using a sign wave normalized to be at -0.1 dB. I can next place that track's fader so that it is assigned to the master output and set the master and track fader both to unity gain. The output meters in SONAR show the signal to be just shy of unity. However when I export that mix and load the exported wave file back into the project, that wave file is about 12 dB below unity. All my rendered mixes are way low and require boosting in a different editor in order to use them for burning to a CD. Why are my exports not reflecting the meters in SONAR X2?
 
Problem 4: the drivers for the PreSonus identify the 16.4.2 ai correctly in PreSonus capture and in Universal Control but in SONAR it is identified as FireStudio StudioLive. This might not be a problem. But it lists among the outputs 10 Aux sends even though this mixer has only 6. Furthermore, I was expecting to see in this driver had input access to the talk-back microphone but that does not appear. I might be mistaken in what I expect but I thought the fire-wire connection between the 16.4.2 ai was for more than the 16 channels and that I would only see as many Aux sends as the mixer actually has. Is this related?
 
I have asked this question in both SONAR and PreSonus user groups.

That changes none of the behavior I am tring to change.

If you have everything routed to your Master bus, and the Master is not assigned to a hardware output, yet you still hear your mix, that alone that tells me this is a monitoring issue.  I'm not familiar enough with the PreSonus specifically (I'll leave that to other owners to chime in on) but you're probably monitoring something other than just the channels that your Master bus should be assigned to.  Look to the monitoring controls on the PreSonus to remedy this.
 
If you aren't listening to the Master track, and the Master track only in SONAR, you aren't really listening to what's being exported to be played back elsewhere. 
 
Kenn
 

NYSR
I am not following what you are saying. The master fader is still behaving like the master fader. It controls the output entirely even though not assigned to anything. And the signal is received at the mixer on channels 1 & 2.

There are several places in Sonar where you may see a label for "master". It sounds like you are not looking at the "Mains" channel strip. The "Mains" is automatically inserted for each available audio card output. The meters and sliders on the Mains actually control what is going from Sonar into your audio interface, and it is that signal which is going to be exported. It can be recognized as a channel strip by default at the extreme right in the console view, the word "master" appears about half way down, and below that are a mute button for each channel of output, between which is  a padlock icon to lock the sliders together then meters and slicers. Look at page 530 of SONAR_X2_Reference_Guide.pdf under the section "Track Inspector Overview."
 
It may be possible to set your sound card as the output from another track or bus, but that is a bad idea, as it bypasses the mains. You would be able to hear it, but what you hear would not be what you will be exporting. Best practice is to be sure that your sound card never appears as an output anywhere in Sonar.

Thanks to all here and elsewhere. It appears all problems are now resolved.