May want to give an Etheregen switch a try? 30 day money back guarantee. Most have found it "smoothes" out their streaming sound by removing hash which enables you to hear a little better resolution from a blacker background. Not sure if that is the same as removing the "fuzzyness and muddled-ness". Probably not quite as good as the already mentioned passive Network acoustics filters, I have't tried one of those yet, but less than half the price also. I have a Plixir LPS on my etherregen.
For sure a short run with a high end ethernet cable made (will make) a smaller difference in sq also, but that is not the best place to start (probably).
It all matters, tackle the digital stream one notch at a time. You need to try things and see what makes a difference in your system to your ears.