General connections:
Laptop USB – UA25 USB
Condenser Mic – UA25 Mic Input 1
Speakers – UA25 rear “Output L/R” (make sure you have the correct cables and/or adapters!!!)
 
 
UA-25
Front:
Digital input switch „off“
Direct Monitoring Switch “off”
Direct Monitoring Volume – fully counterclockwise (if it matters at all)
Adjust output volume to taste
 
Rear:
Advanced Switch “on”
Phantom Power “on” (for Condenser Mic)
You might need to power off the UA25 to make some changes work.. best you power off the UA25 and restart the computer..  
Keep Sonar closed! 
If you speak into the mic now you should hear dead silence from the headphone as well as from the speakers! (turn the “sense” knob clockwise to make sure)
If that’s the case: continue with the next step:
 

Start Sonar. 
In Sonar go to properties and check that only the drivers “Edirol UA-25 Input 1/2" and “Edirol UA-25 Output 1/2" are checked! (or however they appear)
 
Check your Latency. You need to adjust it to something around 8-10ms.. you might go lower, depends on your system a bit,.. but the UA25 tends to distort pretty early when latency is too low. But you need a low latency to get realtime monitoring working..
 

 
Create a NEW project !!!!
On one of the audio tracks you pull the track down to see the hidden options..
You need to set the input to “Edirol UA-25 Left”
Now you need to enable “input monitoring”
The track itself or the inspector (very very left side) has an Icon looking somewaht like this: )))
Press it once !!!
Now speak into the mic !!!
 
Report back !