I have too many things in the air right now to even think of a quiet time to do a Skype.  I have a rehearsal tonight, and Saturday, a performance to record on Sunday and many household things to fix in between.  Next week will be better.  Until then:
 
The total signal level coming from a microphone is controlled via the 'Gain' knob of the channel. There is a knob called 'Phones Level' in the 'Monitor' section of the X32 physical surface. That'll control headphone level, and it's independent of the Main fader (and independent of the Monitor knob).
 
If you've installed the X-USB 4.11 driver mentioned before, then when you go into Sonar>>Edit>>Preferences>>Driver Settings, you should be able to find the X32 ASIO in the pulldown menu for Record Timing Master and Playback Timing Master. Use 'Audio Bit Depth' as 24-bit.  I use Sampling Rate of 48000 for everything now that I'm doing video.  Make sure that the X32 Setup>>Global Sample Rate setting matches. The X32 *does not* change its sampling rate via software control within the project like a 'regular' interface.  The settings must match or you'll get error messages that keep the project from playing. 
 
Once you're able to have the interface known to Sonar, the Sonar>>Preferences>>Control Surfaces should allow you to add Mackie Control as a surface. Choose the USB-MIDI for 'In' and 'Out'.  The X32 menu for Setup>>Remote>>Remote Interface and 'MIDI Control Interface' should be set to 'Card MIDI'.
 
If all that is configured properly, you'll see a little green light on the X32 7-inch display next to 'C:USB', and within the Sonar input selection pull-down in each track there should be a long list of inputs from which you can choose.
 
You're almost there. 
 
 
 
 
 
 

I am almost there Gary. All settings appear correct now and all systems seem to be a go. Okay so here is my current dilemma. I have an audio track with prerecorded audio setup on track 2 of sonar and I can hear it play through my headphones.
 
I have my mic hooked into channel 1 on the X32 and I can hear that through my headphones when I have the solo button on in channel 1. But when I have the solo button on, I can no longer hear track 2 (my music track) through my headphones. And I'd like to be able to sing/record while hearing myself and the music track through my headphones.
 
Q. How do I set up tracks in Sonar to coincide with the tracks on the X32? When I play the music track (track 2), I can control the volume with the track 2 fader on the x32. I can't do this with track1 (my vocal mic) because it doesn't show any signal on Sonar. I honestly don't know how I got the music track to do this. It just happened to be this way when I imported the music to track 2 in Sonar.
 
I guess what I'm ultimately asking is... how do I set track 1 (vocal mic) to be track 1 on X32. What are the settings on Sonar? What are the settings on X32 (if any)? Right now in Sonar, I have track 1 input as: "Stereo X-USB ASIO Driver in 1" and track 1 output set to "MASTER". In track 2, the input is set to "none" and output set to "MASTER".
 
I'm sooooo close!  

Good!
When you have the solo function engaged for a track in Sonar or a channel on the mixer, you're reaching back into the original meaning of the Latin word 'solus' which means 'alone'.  That's why there's nothing else playing.  
 
First you must disabuse yourself of the concept that there's any 1-to-1 relationship between the track number in Sonar and the channel number you'll see/hear it on playback. Also there is no fixed/hard relationship between the track number in Sonar and the input channel you choose. Those relationships will die in the last days of tape machines and analog consoles. 
 
For example, you can create a Sonar project with 16 empty tracks, and arbitrarily choose track-7 to be from input-1 of the X32.  In fact, you can choose track-3, track-7, and track-11 to all concurrently capture input-1 from the X32.  They will all default to playing back on Master.  You can also sprinkle stereo tracks within your population of mono tracks, so track-5, track-8, and track-10 can be stereo tracks while all the others are mono. There's no real significance to the track number other than a way to label/note what it is...like a flight number.
 
The pre-recorded or captured tracks in Sonar will play back on the 'Master' by default, which is coming out on the X-USB via 'Card 1/2' into the X32 which goes to the XLR 15/16 which goes to your Rokit speakers.  You can vary the playback volume of the Sonar tracks using the faders in Sonar.  You can control the faders in Sonar with the mouse or with the Mackie Control faders that are controlling the tracks. 
 
The volume of the vocal microphone before it becomes captured/recorded by Sonar is controlled by the gain setting its X32 channel and not the fader position of the X32.  *The X32 fader position does not affect the initially recorded level!*  That's because the recorded level going into Sonar is picked off of the X32 right after the preamp and A/D converter, before any EQ, compression, effects, or fader stuff ever touches it. 
 
If your Routing tab has Local 1-8, and Card-out is taking 1-8 into Sonar, then in Sonar the first 8 inputs are just the way you'd expect: Channel-1 is 1-left, and Channel-2 is 1-right in Sonar. 
 
Let me know if this gets you over the last hurdle.

Garymedia:
You're an amazing guy!  I wish I had had someone like you around when I started on SONAR!

I am currently using the little brother of the X32, the XR18 as my interface.  I do much the same thing as you, playback one track and record on another.  In order to do this you need to bring up the X32 app (The one that controls the X32 Or on the Console and make sure the INPUT for the track you want to record is Analog.  Then you can control the volume of the item being recorded with the track fader and the volume of the rest of the recorded tracks with the volume of the bus or channel you have the master bus set to in Sonar.  I hope this makes sense!
 

I am currently using the little brother of the X32, the XR18 as my interface.  I do much the same thing as you, playback one track and record on another.  In order to do this you need to bring up the X32 app (The one that controls the X32 Or on the Console and make sure the INPUT for the track you want to record is Analog.  Then you can control the volume of the item being recorded with the track fader and the volume of the rest of the recorded tracks with the volume of the bus or channel you have the master bus set to in Sonar.  I hope this makes sense!