I wonder if there is some way you could connect another PC directly to the outgoing stream. That would verify if the PC is encoding right, and not the server having issues with redirecting the sound.
In my old electronics class, we had a troubleshooting technique that would take a circuit with a problem and "cut in half". If the half way point worked, then go forward half way. If not, go back half way. You keep halving things until you find the answer. Worked back then, it should work now on this issue.