Running through powerline is really easy and neat but I think you can suffer from poorer SQ because of it. I did try to compare the system through powerline vs 15m of shielded cable straight out of the router and SQ was indistinguishable on my system at the time.
Maybe the shielding also did not help, it wasnt designed for audio. I have also improved my system much since that early trial.
What I have discovered recently is that when I used an audio network switch called an etherRegen, I achieved a very marked improvement in SQ and I think some of that delta is because of the powerline ethernet.
There is much more to ethernet SQ than conventional wisdom dictates for sure.
You may benefit from putting a switch near to the hifi and then feeding a short cable to the system. There are some good threads on computer audio forums on shunting the power supply to ground on relatively normal ethernet switches like netgear and getting a good jump in SQ.
Typically wired is better than wireless but that could also be subject to the system so try that too.
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