If you load a file in Karaoke Surgeon, start it playing and hear no sound, then the issue is likely with the
default audio playback device being used. 

Open the program.  Go to the Options button >> Other.

In this tab, the first item will be select output device.  Make sure the device selected here
is your default audio ouput used for the computer.  Change it as necessary.  Then save your changes.
Now close the program, reopen it and then open and play a file.

If this doesn't solve your problem, please complete a support ticket.