Ha ha - I tested it, and I can both bounce a track within the project, and export the complete project, all without any audio interface connected.
So if I'm working inside the box only, whatever audio interface I have has absolutely no affect on the sound quality of the rendered file, as all the processing is done internally within the DAW?
So if I was to make a song in Sonar, and upload to eg Soundcloud or make an MP3 and send it to someone - I cuod have a $50 interface, or a $5000 interface and it wouldn't make any difference?