The answer is no.
So what objective proof would you like considering we don’t know why Ethernet cables sound different, and what we could possibly measure that could show it?
Just a regular audio analyzer won’t cut it.
If you need a hypothesis, at least in the US AudioQuest can be reached at +1 800 747 2770.
Synergistic Research is at +1 (949) 476-0000.
Or perhaps contact Telegartner and ask why they bother to make these:
Or contact Buffalo and ask why a company that is so highly regarded in the networking world risks sullying that reputation by offering audiophile network switches through their Melco subsidiary.
Oh that’s right, it’s all to sell product at a premium to suckers.
there are plenty of companies across all fields which are happy to sell snake oil
There are many who call dCS’ products snake oil too, so it’s all in the eye of the beholder.
Uh oh…I guess time to sell my Rossini 
Who knows. 
Recently a guy - in all honesty - told me my Vivaldi One was no better than his Oppo DAC of $ 1.000,- because they measure similarly. If you think that’s funny, you’re absolutely right. But let’s think about it: how much different does your Rossini sound from Bartók…? Or from Vivaldi for that matter. But indeed they also measure almost the same.
Now, transfer this example to the current topic of Ethernet cables and we just might be getting somewhere.
Vincent
That is interesting. Since they all measure the same would you like to trade your Vivaldi One for my Rossini?
I will even throw in my Rossini Clock
After all…they measure the same. Come on…Pretty please?
One can always ask…
I bought a Porsche 4e-hybrid and the delivery date is in September, I added the Bose stereo option….Oh ! Nothing to do with the subject of this thread…but who cares ?
Even a basic oscilloscope can measure to 1,000 times beyond human hearing. Any actual reduction in noise will be measurable. But so far it’s been crickets from the Audiophile Ethernet cable vendors/believers 
Did you actually read what you quoted? Let me help you, here’s some of what Telegaertner says about the MFP8 connector.
MFP8: For new freedom in structured cabling
Here’s the situation: An existing network needs extending. A cable link needs to be repaired or replaced. A peripheral device needs to be connected quickly. Your customer expects a fast and reliable solution but you don’t have a cable assembly ready at hand. Sound familiar?
Now you can keep cool when faced with such demands – with the field assembly MFP8 RJ45 plug series developed by Telegärtner.
Less fuss. More flexibility.
The MFP8 plug series enables time-saving and efficient onsite assembly for all networks, from Voice right through to 40 Gigabit Ethernet. It can be assembled on all standard types of cable in just 60 seconds – and no special tools are required.
Whether in the office, data centers, in industry or in home networks – the MFP8 plug series offers unprecedented flexibility and saves time and money on installation, repairs and maintenance.
So, where does is say reduction in Ethernet cable noise? Or improvement in sound quality? Or any of the other things that proponents of Audiophile Ethernet cables like to claim??
Absolutely nowhere. Not even on the full product brochure. In fact, the MFP8’s detailed specs are all about full compliance to IEEE/TIA/IEC specifications, thank you very much.
ps: As for Shunyata and Buffalo… I think Greg’s pretty much covered it 
I just feel sorry for you that you require some scientific explanation or to be shown something on a piece of la equipment before just listening for a difference.
Wanting to know why something makes a difference - nothing wrong with that.
Needing to know beforehand - that IMHO is sad, but it’s all up to you.
Note I never said the Telegartner connector improved sound, but it is what’s used on AudioQuest cables and there have to be reasons people pay a huge premium for them; you could hire a full time member of an IT staff for what a typical data center would pay for Telegartners as compared to bulk connectors that also meet specs.
As I’ve said before, using a scope to try and see why there are differences in sound may well be the same as saying all cables sound the same when using a battery and a LED as your test gear.
Maybe you’re referring to someone else, not me.
As I’ve explained before within this thread alone, I have absolutely no qualms about giving something a try before I dig into it further (like with the AudioQuest Diamond RJ/E cable for example).
The fundamental difference between you and I is that I don’t just blindly believe everything I think I’m hearing, or everything someone trying to sell me a cable says - the entire process of human hearing is far too fallible, especially with minute differences. No doubt a sip of your favourite cognac will throw off your hearing far more than your favourite power cable 
I don’t blindly believe what I hear and especially what is said by vendors (it’s interesting how you often manage to turn a defense of your position into a not-so-subtle personal insult.)
I decide I’ve heard an improvement after careful listening to a variety of material, swapping of cables over several days and often realizing I am now disappointed to listen to what I had.
It’s also fun when people who are not audiophiles are listening, I change cables and they ask “What did you just do, it sounds so different now.”
As I’ve mentioned, I decline to purchase perhaps 95% of the gear I bring home to audition, but when it’s something I will purchase I can often hear it almost immediately.
I’ll give the example of the Ayre QX-5 Twenty, which every reviewer and my dealer thought was the best DAC they’d heard (for the price) and despite borrowing it for a week twice, three months apart, I came to the same conclusion after ten minutes each time: those reviewers obviously didn’t have a Wadia at home.
Also of my dCS experience - both the Bartók and Rossini Player came nowhere near what I heard with the Wadia; it was only with the Rossini Clock that the sound surpassed what I already had (for nearly 3x the price; I never would have been looking in the first place had Fine Sounds not effectively shot Wadia in the head when they purchased it, killing off the 24/192 upgrade they were ready to ship, and a recommendation I got from a friend at RMAF 2019.)
I will say a big exception was the last Theta DAC I auditioned - so much detail that sounded so good whenever I started listening - and always induced listener fatigue within ten minutes.
But not once did I need to know why or see measurements. I don’t know if I’ve ever even looked at published specs or tests of the RP.
Western education makes us believe that there is an objective reality out there. The role of our mind in perception is often left out. There is this one reality and that’s it. Our belief in one objective reality can lead to problems when we discuss our hobby.
The role of our mind in perception is crucial. Here are three examples:
(1) A film director will see a very different movie from his friend who is with him in the cinema and is a film aficionado. The father whose child plays in the football team will see a very different game than the referee or the child’s school friend.
(2) Another way to approach this would be to look at exceptional minds. How someone on the autism spectrum perceives “objective reality” can be radically different from how someone else perceives it. How Brahms perceived music must have been very different from how I perceive music.
(3) Or yet another way of looking at it - what is a table? It depends on who we ask. From my point of view, I can knock on it and know that it is made of wood. I see that it is made of legs and a table top. From that I can conclude that it is composed of parts. An expert in physics will give a very different answer. So will an expert in chemistry or one in carpentry.
These examples illustrate that our own minds play a key role in how we see, hear, taste, feel and smell the world. It is not the case that there is a sensation and that sensation automatically and invariably leads to the same result in cognition. Rather, imprints in the storehouse consciousness lead to events in regular consciousness. These imprints are a matter of dispositions and conditioning. Should you be interested in more in depth material from authors with greater understanding than myself, I’m more than happy to point you there. I’m a PM away.
Ah, one more thing with a touch of humour - we know about the placebo effect - people feel better when they are given pills that contain no active ingredient. We all know what that means in our hobby. The “invisible gorilla” is the reverse placebo effect - not noticing something that is clearly there. Check it out. It’s hilarious how fallible we all are.
http://www.theinvisiblegorilla.com/index.html
There’s a link to Videos and Demos on the left where you can see the study setup. I had to silently laugh about myself. 
Information is not knowledge.
Knowledge is not wisdom.
Wisdom is not truth.
Truth is not beauty.
Beauty is not love.
Love is not music.
Music is THE BEST.
― Frank Zappa
(withdrawn)
Still on Ethernet cables …I got the Covid virus 2 months ago…I was used to drink Zero Coke…and suddenly it was impossible to drink it anymore, it was an awful taste, I could smell all the chemical products inside as if I had got a super power instead of a virus….Now when I drink a Zero Coke, I like it, the taste is excellent and I don’t smell any chemical product inside…so a little thing completely changed my tastes, amazing ! Now I understand much better when someone hears something completely different from what I can hear myself…
I read between the lines you are framing the thread more narrowly than I do. My framing would be ‘ethernet cable in the context of an audio system’. I reread parts of the thread and how it evolved - this frame holds. From there on it should be permissible to make a step and talk about the listener. Even more so as contributors to the thread disagreed more than once.
We discuss with dedication the gear but less so the listener. There’s plenty to discover when we examine what happens in our consiousness while listening to music. A focus on the listener can even improve our enjoyment of the music. I can attest to that as I am willingly practicing different modes of listening. It has become a much loved part of my audio hobby. Just to give one example - when some time has elapsed after sitting down and spinning a record the music sounds better. That’s not the system doing anything. All gear is on 24/7. That’s discursive thinking subsiding and the mind becoming calm. There is more bandwidth available for raw awareness where in the beginning discursive thought occupied most of that space.
Science says no but…
Chris, sorry to hear about the COVID experience, but that’s an actual objective thing that happened. And it changed your experience in ways they represent a common outcome compared to others. It neither demonstrates how different Ethernet cables could deliver different SQ, nor why, in the absence of any other difference, in a system, cognitive bias should not be the suspected primary culprit.
On that topic, I will offer this link to a (barely) moderately similar development in the wine-tasting field, a realm marked by lots of objectivity and subjectivity. And the seeking of pleasure.
Just to clarify something: I don’t require a scientific explanation of why/how one component sounds different, or even one cable, before I decide to audition it. That is an exaggeration of my view by another poster. In fact, I haven’t been talking about DACs or analog cables, many of which do sound quite different to my ears (and none of which have anything to do with this thread). And I don’t need to know the why to know that they do. When I find something I like, as in the case of the MSB or dCS, or the TotalDAC and NADAC before, etc, I like to learn about the design and engineering aspects. That’s not this thread. This thread is about Ethernet cables. And for (not just) me, there are reasons to be more suspect about their ability to make an audible SQ difference in a stack as well-engineered as a dCS Vivaldi stack. So, when someone proclaims such a difference, I do ask “how can that be?”. Especially something of which the abstract function is so simple, and for which the engineers of some of the finest audio product in the world have specified the simplest of specs. What could make that difference? I haven’t asked anyone to reveal Shunyata or AQ engineering trade secrets. I have simply asked abstractly how, before I go pulling out components to swap cables, in a system that is already optimized for low/no noise, optical isolation, proper grounding, etc.—what’s the theory? One has yet to be offered in this or any other forum I have read. And for this audiophool, “try it; you might like it”—a recommendation I will gladly and enthusiastically embrace on even a no-name bottle of Pinot Noir or indie film if I have reason to trust your taste—just isn’t very persuasive. To my ears, it’s the very embodiment of cognitive bias.