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

@johannm yeah these types of tweaks like iFi are low cost and depending on a system can bring some positive results. The iFi filter didn’t make things worse in my setup. I stick to bare necessary minimum when it comes to network toys. I played with FMC units from amazon (I know not the best in class) and found them to be useless at best. No plans to explore better quality FMC. I dig the sound I have now - non-existent noise floor, smooth, detailed and natural. It’s important to keep all this noisy network crap like routers and switches away from audio components and plugged into a different circuit. 

I will second the fact that the better streamer and DAC [separates] will be the biggest improvement and the most costly, but do it first anyway.   Then do your tweaks.  Smoothlan works like it should.  Network switch from Netgear $40 anywhere is an easy  recommendation.  You will notice these improvements more if you have a revealing system.

@boxcarman 

+1

I agree to keep the digital path as simple as possible.  I feed my Eversolo DMP A8 directly from router with an above average CAT 6. Then SHORT Bluejeans XLRs to AHB2. From AHB2 to Focals 948 withe proprietary Benchmark cables. No cables for thousands of dollars but I have clean and noiseless sound.

I have not seen that much improvement $-for-$ with different Ethernet cables however one device has made a notable improvement and that's the Uptone-Audio EtherREGEN.  Installing it between my router and streamer (Innuos ZENith MK-III), I was able to instantly tell that the noise floor lowered, and fine details emerged in the music.  A more realistic portrayal.  Definitely the most sonic performance improvement $-for-$ I've had in my system !  Seems like a number of others in this thread also like the Uptone-Audio EtherREGEN too.