Quite simply, because the data rates for Cat7 and Cat8 require much higher operating frequencies, which necessitates the shielding. But you do not need this for streaming media in the home.
When replying, especially when seeking clarification, please use an interrogative. Your earlier posts used statements, which may not have been your intention.
Sometimes we imagine things. Itās as simple as that.
I used SOtM dCBL-CAT6 before, now SQ is better with the short bits.
Thank you all. I will try a plain Cat6 cable. Turning the Nucleus off and on only didnāt help. There is a difference in sound caused by unplugging and plugging back the ethernet cable to the Nucleus, but it does not always happen and does not seem always to be the same amount of change. I can only think that there is something not quite right about the connection. Iām human and am playing different music at different times so this isnāt scientific. As to why sound might deteriorateāperhaps I bumped the cable? I donāt know what a ground loop is.
As for what I have here. There is a TP link router, Starlight Cat8 Wireworld ethernet cable (the cables do have arrows for direction) to network switch (donāt know brand) Nucleus (not plus, running the update before the current one) attached to network switch with Starlight Cat 8. The Remote is a MacBook Pro 2021 14 inch (same update). An Aqua LinQ (HQPlayer embedded) is the streamer, attached to the network switch with same cable, and attached to Aqua Formula DAC with Platinum CAT 8 cable. Hope that is enough.
Iām not imagining the change in sound. Both of us have heard it, independently. I agree that it is odd. That is why Iāve asked for help. Iām really grateful
Transmission is handled by TCP/IP. If there are any errors during transmission, networking handles it. RAAT allows Roon to control endpoints; it send the music, but also can provide artwork or device controls.
Take a look at the help centre.
And this thread for more detail.
This would be my first port of call.
As others have explained above, although they may physically fit the RJ45 socket on your home router or Nucleus, CAT 7 or 8 cables arenāt designed to work with those devices.
Youāre effectively using the wrong cable for the job and the shielded / metal plugs on your CAT 8 cables are potentially causing you unwanted issues on your analog audio devices (ie. ground loops, the cable acting as an aerial if only connected at one end on poorly designed kit) as these devices werenāt designed to be used with shielded Ethernet cables.
By contrast the plastic RJ45 connectors on a bog-standard standard CAT 5e or CAT 6 cable ensure the units are isolated from each other as intended / designed.
CAT 5e or CAT 6 cables (not CAT 6e which uses shielded connectors) are what you should be using with your home router / Nucleus / streamer. With your current equipment the numbers 7 and 8 donāt mean better, it means a different and potentially incompatible standard that will potentially cause you issues.
Petrabytes of data is reliably transferred over millions of miles of CAT 6 and CAT 5e cables every second, itās a pretty robust standard and far exceeds the requirements of Roon.
Thank you.
The audiophile cable from SOtM has metal ends and they are connected by a shield, I measured the resistance and itās zero Ohm ā¦ I donāt think thatās right either.
There IS a minimum length for Ethernet cables too at least between 2 devices. While very short patch cables exist they are intended normally to patch to a longer cable in a patch bay to elsewhere in a building.
Iirc the minimum length is 1m or ~39.5ā
This means both are connected through the cable shielding. This is correct for Cat7, where the connectors should be grounded at both ends. However, if your terminations, i.e., router, switch, streamer etc., do not support this, it wonāt perform as intended, and is a waste of money.
Not only will it not be grounded end to end, one end might act like an antenna to the end the might be grounded.
Thank you all for the valuable knowledge, I know a little more again.
Just a thought: is the Ethernet cable resting on carpet or some other surface? My thought is that their is some environmental influence that is being induced, over time, that is being transmitted, especially via the cables shield or other cable materials, and is being then transmitted by the connectors. Following others guidance use a well made CAT 6 UTP cable and see if that helps.
That is just a thought sparked by audiophile myths, lacking any technical background.
Next youāll be telling me these are a scam! 
Itās not just the bitsā¦noise gets transmitted in myriad ways, whether via induction, conduction, or OTA (RFI & EMI).
Magical thinking is deeply anchored in our collective unconsciousā¦
More wisdom from the crowd: āStacks of walnut and maple wood flooring samples also make good supports. (These are the so-called tone woods, which impart a splash of pleasant seasoning. Other wood varieties, such as mahogany, pine, or bamboo, donāt sound as good.)ā [from the review posted above]
Personally, I think bamboo sounds just fine.
Indeed. But does this ānoiseā have any impact on SQ and, if so, how? With digital data, either itās received, or it isnāt. You canāt have noisy bits or not noisy bits - theyāre just bits. Any other noise that might be present in an ethernet cable will be rejected by any half-decent DAC or other item of networking gear. Noise, in the digital domain at least, is another of those audiophile myths, for which there are a lot of expensive solutions ā¦ itās just the problem thatās missing.