Firstly, go to the settings of your interface
Try making the sample rate 44.1 - this will have to match what Sonar is set to but you have to start somewhere so do that here
Try setting the number of samples parameter to 256 - it's a reasonable starting point
Now BEFORE going into Sonar, test out the sound of playing a song through Windows Media Player. Sound OK?
Now go into Sonar - don't bother getting into a project yet - go to Edit>Preferences>Audio>Playback and Recording
What driver mode are you running in? Set it to ASIO then click Apply
Now click on Driver Settings on the left
Set the Sample Rate to 44.1 to match the interface settings
Click Apply
Close out of this
Open a new project with Normal template
Insert an audio track
Click on the number 1 on the left side of the track to select it
Click File>Edit>Import Audio and import some MP3 or WMA file, this will load it to track 1
Now click Play or hit the space bar
How does it sound? Does it sound?
The above just checks a simple audio file for playback outside of Sonar and also within Sonar
Please post results
Bob Bone