Relationship between Ethernet Switch and SQ

@lalitk et al, some partial empirical report-out as changes have occurred in my system: 

1. As noted earlier, I found LHY switch was a small negative on sound quality (as compared to no switch, if one can avoid the need).  I have not re-introduced it in the chain, but will test as you suggest.

2. ENO filter re-validated as a small improvement on sound quality.

3. Roon sounds worse than Manic Moose (native player, also known as Music Player Daemon or MPD) with Bryston BDP players.  There was another thread where people were debating whether Roon did or could have negative impact on SQ.  I hear some (at least as compared with BDP + Manic Moose combo, which may be a magic pairing).  This is streaming Tidal lossless, PCM and feeding Lampizator DAC.  Using Roon B Nucleus with an LHY LPS (LPS80VA). I was a Roon lover until I realized I would want MPD for critical listening...not sure I will want Roon for part-time use.  

5. I did get the Cat8 cable you recommended, and it is an impressive cable in the beefy connections and double shielding.  I like it...but have not yet compared it with the old Cat5 in the walls for SQ. https://www.amazon.com/dp/B089N9HCSG?ref=ppx_yo2ov_dt_b_product_details&th=1

6. BDP3 shipping will be delayed a bit; all the above is using BDP2 still.  

So still need to compare CAT cable and give the LHY switch another chance.  I also changed routers, which adds variability to whatever I thought I heard before (never realized Roon could be a negative on SQ before, but I wasn't looking for it either). 

@mathiasmingus thanks for the follow up.
Oh yeah the LinkUp cable is really nice. Give it some time to settle though. 
On Roon vs native streamer UI sound quality…in my experience with two dedicated streamers, Auralic Aries G1 and Lumin U1 Mini, I definitely heard the Auralic Lightning DS sound better than Roon, but with Lumin U1 Mini it was really close between the Lumin app and Roon. So I restarted my Roon subscription when I got the Lumin. I actually preferred the less “digital” presentation with Roon using U1 Mini as end point. That was a blessing because the Lumin app sucks. 
So it all depends on a streamer and what has more synergy with your setup. 

My LHY switch up and died on me a some weeks back.  It was 10 months old at the time so still under warranty.  With help from Singapore, I diagnosed the problem- shorted circuit on the ethernet card.  They sent me a replacement board and it is back up and running.  Meanwhile, I couldn’t be without music and I could definitely hear a difference without the LHY so I bought the English Electric 8 switch.  I like the sound of it a little better than the LHY.  Now I am keeping the EE8 in my audio system.  

My plan was to sell the LHY after a month or two, to insure the repair held; but I inserted it at the TV end of my long ethernet cable from the EE8 to the TV.  Surprisingly, it made an already great TV picture even better.  So the LHY is staying.  

I have no doubts now that these audio grade switches matter just as much as a DAC or an amp.  I hope I never hear a $3000 switch in my system.  That’s the thing about audio- our systems sound great, until we hear something better. 

More info:  I ran what it supposed to be a 75 foot (maybe it is a 100ft cable), CAT7 ethernet cable from the Audio grade network switch to my Apple TV box.  That was a major improvement in the streaming picture on my OLED TV.  The fact that putting the LHY switch- a second audio grade network switch downstream of this long cable run making the picture even better tells me these ethernet cables still pick up some level of noise.  

Also, I tried my fiber optic link with LPS powered FMC’s and that added some graininess to the TV picture.  So overall, I find the Audio grade switches to be the best option for music and video.

@mathiasmingus

Thanks for the update. IME, ROON implementation is one of the main reason why end user would experience inconsistency in SQ. Every manufacturer or designer doing their best to integrate ROON and tweak their hardware for best possible outcome. As @audphile1 pointed out, ROON SQ greatly varies due to the approach in the implementation by each manufacturer. Some manufacturers excelling and others couldn’t care less as long as they are meeting the ‘ROON endpoint’ specifications. 

Coming back to your system, If I may make a suggestion to strategically introduce each change one at a time. Starting with LinkUp cable, let it break-in for atleast 250 hours before you introduce next upgrade, i.e. LHY switch. Once all the components are fully broken-in, then reverse the process for A/B comparison. Listen for extended periods, especially LAN cable. Streamers typically buffers or cache incoming bitstream so swapping LAN cables on short intervals may not allow you to discern any differences.

Good luck and have fun!