Sometimes "power line" products can cause problems for audio, especially if you have a good system that shows flaws easily. I also think that grounding issues can become an issue. While I don't usually recommend power conditioners, sometimes when dealing with poor eletrical issues, they can solve some problems.
Network data is delivered in packets, so the problem is probably not with the data signal, but from the electrical and mechanical interference.
What devices and DAC are you using? You might want to just use a wifi router and extender to get data to the area, but wifi connections can also have problems depending on how you are using them.