[Solved] Can I Adjust Monitoring Levels in Sonar that Doesn't Affect Record Levels?

The record fader in Sonar has no effect on the recorded signal. With that being the case you can adjust it all you want for monitoring. I don't recommend that because you wont get an accurate meter level. In your case it could be helpful though.

You could set up a cue mix like you'd do on a console and monitor through a different set of outputs.
 
Adjust each channel with the send level to a monitor buss that is sent to an output that feeds your headphones. 
 
Hope that makes since! lol

what sound card are you using?
For many years, I have used a smal mixer to create a simple matrix for monitoring purposes.
 
On one (stereo) channel of this mixer I have the output of my DAW.  Everything already in the project plays through this channel.  Right next to it on another stereo track (or two mono), I have the "monitor mix", which is everything that is currently being recorded.  This allows tactile, instant control over the level relationship between what is old, and what is new (so to speak).   My interface is the profire 2626, so it is also possible to make several sub mixes for different headphone mixes.  I rarely find it necessary to do so.  90% of the time, we are recording one thing- one person at a time.  Having very easy control over how well they hear themselves as compared to the existing music is a MUST for me.  This simple setup also allows me to turn up the headphone level for musicians without affecting the level that I hear in the control room.  This is also a must for me.
 
If it helps, I can elaborate or send pics.  
No doubt, all of this can be done within the software environment if you have the right interface.
Still, I like having the faders right there for adjusting monitor mix.