I understand that you are having some issues with the Slingbox audio signal.
Most of the times, this issue is related to a wrong cables connection. With this in mind, I recommend you to check the following link and follow the recommended steps.
Now, if you are still using the S/PDIF audio cable, I recommend you to run the configuration for TV sources one more time. If you are using the web-based application, the process will recognize the S/PDIF connection automatically. If you are using the SlingPlayer software version, you'll need to select the audio output among the available options (digital and analog signals).
Make sure to follow these recommendations and let us know how it works for you.