Do upgraded LAN cables/purifiers/switch box make a difference. What is recommended, if so?

Another negative for the Amazon or cheapo media converters. I've been through the generic stuff fed by wall warts and lps, they both give and take away. A fully positive experience found in quality streaming products produced solely for music streaming, the Sonore equipment superior here. Also, one should experiment with transceivers in these media converters, not all created equal, the Finisar industrial grade 1475 is very nice. I also like silver for cabling, all silver or higher percentage in copper cables. 

@antigrunge2 

Think in future about making apodictic statements that are patently false!

The word apodictic is new to me. Thank you for broadening my vocabulary!

Your ability to contradict yourself in a short paragraph is prodiguous.

In the spirit of mutual linguistic assistance: It’s prodigious, not prodiguous.

At issue here is the fact that some people just can’t wrap their heads around the fact that digital is not analog, and keep trying to impart analog characteristics to the digital realm. It’s the equivalent of someone in 1910 throwing a blanket across the engine of an automobile on a cold winter night.

1910 automobile owner: And why do you reckon they call’em horsepower, eh? They’re horses all right, they’re just very small. They still need warmth. 

@roadcykler  In your system that is...

No, they make no objective difference in the sound from a stereo.

@devinplombier 

While analogue and digital issues are distinct in this case they are comingled: EMI/RMI noise on cables affects the D/A conversin since your bit perfect bits are arriving with messed up syncronicity and bent shape which both lead to increased jitter: in other words: analogue is messing up digital. hence your horsepower analogy is fallacious