I wanted to provide a quick update ...

I received the Supra Cat8 ethernet cable a couple of days ago, and tried a few different configurations. The best config that I settled on is something like this ...

Media Room >> Wall jack >> Supra Cat 8 >> Cheap router (with ifi power supply) >> Network Acoustics ethernet cable >> Eno filter >> Network Acoustics ethernet cable (short) >> Zenith MK3 >> Silnote Epirus Elite Master USB cable >> Luxman DA-06

FWIW, the Supra Cat 8 is clearly better in my system compared to the generic Cat 6 I was using earlier. I know this is going to rile up some folks, but I hear what I hear. The changes are subtle but the Supra Cat 8 has clearly reduced the noise floor, and removed the tiny bit of digital harshness that existed before. Thanks @lalitk for the suggestion.

But I must say the star of the show is Eno. I tried to remove it from the chain and it's one of those things that you don't know what you're missing until you remove it from the chain. It provides a blacker background and does a great job of getting digital a few steps closer to vinyl. I thought my system was pretty decent to begin with, but Eno + Supra Cat 8 + Innuos Zenith has really elevated the performance to new levels. 

I think I'm done for 2021 :)

Great article in Absolute Sound about adding Fiber Optical connectivity to your system:

https://www.theabsolutesound.com/articles/how-to-optimize-digital-streaming-with-optical-fiber

General suggestions I have implemented and found to improve system reproduction quality:

Use fiber connections whenever possible. I have a fiber network backbone connectivity from my network cable modem through the rest of my system’s switches.  This is an inexpensive upgrade which increases network performance and money better spent than on add-on products such as noise filters.

Use high quality network switches such as a Cisco SG-350-28 or Catalyst 1000. These are managed switches and thus require some networking savvy to implement. I use the Cisco SG-350-28 28 port switches which can accommodate four fiber connections per switch as well as 24 RJ45 Ethernet connections. The Cisco Catalyst 1000 series which I have also used require more advanced Cisco knowledge and so unless you know what you are doing, the SG-350 web management interface is much better. Cost per switch is under $500 per unit. Using the management interface, you can see what is going on with the network and can show things such as high error rates which would be a key performance indicator.

I have found that high quality cables such as Blue Jeans cable Cat 6 or 6a, which come with a sheet actually documenting their performance with an HP cable tester, to be more than adequate.

An Ethernet connection in my experience from your switch to your DAC/Streamer is preferred to USB.

If possible, connect mesh routers together with  Ethernet cable or fiber backhaul runs for best performance.

I found that the Small Green Computer Fiber to Copper OPTICALMODULE DELUXE with their 7V LINEAR POWER SUPPLY works very well feeding my Mytek Manhattan II DAC.

Focus on building a better network before trying to fine tune with add-on accessories and you MAY find that they are not required.

The Innuos PhoenixNet Switch was mentioned in this thread. I was curious if anyone has tried this ethernet switch and had a chance to compare to other switches?

@nmolnar 

f possible, connect mesh routers together with  Ethernet cable or fiber backhaul runs for best performance.

I'm curious why connecting 'mesh routers together with ethernet cable' vs. the ethernet cable directly from my router in the study is going to provide improvements. Can you elaborate on this point if you don't mind?

BTW, I use a Google Nest Wifi mesh system and tried it in my media room, but I didn't feel it provided any improvement, so I went back to regular ethernet the way it was. I agree with you about the benefits of fiber optics, but as I said earlier, given the over 200 foot distance and other reasons, it is not feasible to run a long fiber cable at the moment. But that is something I might consider down the line for sure.

Also, I own an SGC opticalModule Deluxe that I'n using with my opticalRendu in my study. This setup used to be in the media room before I got the Innuos Zenith MK3 and Eno filter. Initially, I didn't feel that the Zenith + Eno combo was better than opticalRendu. But I kid you not, after putting over 50 hours on the Zenith, it has far surpassed the opticalRendu. My main system has never sounded this good.

@timo62 -- the PhoenixNET switch definitely sounds very interesting. It's a little pricey but if you consider the alternative, i.e. the jumbled mess of wires and boxes, it's actually not a bad deal, and not really that much more expensive considering everything else. What gives me pause is that there is a dearth of reviews and feedback from actual owners. Of course, you have your usual professionally written reviews but that's neither here nor there.

I've been doing some research ... okay, what I really mean is asking a lot of people whose opinions I trust ... and I'm of the opinion that I'm better off putting my money towards a DAC which has a really good built-in clock and employs better isolation techniques before I invest in an external switch like Phoenix. In the meantime, I might try a cheaper alternative like EtherRegen to see if it makes a difference. But to be honest, my current configuration (Supra Cat8 >> Eno >> Zenith >> DAC) is sounding splendid! I don't think my system has ever sounded this good. I'll probably just enjoy what I have for the time being.