Thanks for posting!
The audio connection is an all-digital path from the Surface Pro 2 -> the Plugable dock (http://plugable.com/products/ud-3900/ ) -> HDMI -> TV. It’s only the last hop to the TV’s speakers that’s analog.
Digital audio generally suffers from drop outs and latency if something is going wrong, but usually wouldn’t be described as fuzzy / cracked – that sounds a bit more like an analog issue.
One way of intercepting in the middle of the chain to rule this in or out – if you have any headphones around and can connect them to the 3.5mm audio output jack on the UD-3900 dock, and see if you’re getting the same audio issue at that point.
Do you have headphones around to be able to do that check? If so, can you let us know how that goes? With that, we’ll have a little data on what audio hop might be behind the drop in quality that you’re experiencing.
Again, thanks for posting!