I agree with antigrunge2 about the etherRegen (eR) between a standard switch and the streamer. After doing this, I added another eR in series. Now my network: standard switch thru cat6 to eR thru fiber optic to another eR through my best cat6 cable into streamer (an HQPlayer NAA in my case). The SMPS that comes with eR is good. A linear PS can make an additional, subtle, improvement.
Without the eR in the chain, a linear power supply on the std switch made a big difference. With the eR in place this improvement is subtle.