Sometimes, the difference is subtle (like the difference between the two Netgear switches). But in this case, the difference was a sensitive one, and it was obvious.
Anyway, this test does not mean that the sound improvement forcefully resulted from a better performance of EtherRegen. It’s possible that the improvement was due to its synchronization with the other devices of the setup that were connected to the same master clock.
That’s not what it does. It just makes sure that the internal receive buffers don’t overflow or underflow. If the USB rate is a bit too high compared to the D/A conversion rate, it is slowed down, and if it’s a bit too low, it is sped up. The D/A conversion rate depends solely on the DAC’s clock.
Given the above description of how async USB works, it should be clear that the timing of network streaming is not relevant as long as the overall transfer rate is maintained such that the D/A conversion buffers don’t overflow or underflow.
Using I2S simply bypasses the DAC’s internal clock and buffering. Everything else stays the same, it’s just done outside of the DAC instead of under its chassis.
The main purpose is to prevent long-term problems due to the inevitable slight differences between the clock frequencies on the host and that on the target device. Without feedback, these errors would eventually result in the buffer on the target device emptying or over-filling. Using asynchronous mode with feedback allows the target device to “control the clock” insofar as it can clock data to the DAC driven by the local, presumably accurate sample clock. It does not affect short-term timing which is driven by the number of samples the host chooses to transfer per USB frame period. Unless the audio sample rate is an exact multiple of the USB frame rate (8 kHz) the number of samples per frame will not be constant so there will inevitably be short term timing fluctuations; the asynchronous feedback does not change that. (Which of course is why there has to be a buffer to de-coupling the USB bus from the DAC.) What the feedback does do is cause the host to occasionally insert an extra sample or remove a sample to prevent long-term drift from accumulating.
Hmmm…
It is not possible for a fancy clock to improve performance of an Ethernet switch when 50ppm is the requirement. Most enterprise and consumer copper gigabit Ethernet clocks run at around 25ppm; a TCXO at sub 1ppm is like using a digital stopwatch with 0.001sec of granularity to work out when your birthday is - a calendar is adequate for this.
An Ethernet switch clock does not synchronise with any other connected upstream or downstream device. The clock inside a switch is for providing a reference point for embedding the timing signals in transmitted data frames - Ethernet transmission is asynchronous.
If you want to understand the how and why of asynchronous transmission, go investigate Manchester Encoding as a start point - how things worked in the 10BASE-X days. As speeds have increased down the years, so too have improvements to encoding the timing signal within the data frames being sent. On Gigabit Ethernet, the timing signal is encoded using 8B1Q4 method (subsequently the 4D-PAM5 encoding method is performed on top of that enabling the 5 voltage levels to be used in transmission).
You can find on the internet articles that say anything, and the contrary.
It’s necessary to listen to the feedback from other users that you know, and that you trust their appreciations.
But most importantly, it’s necessary to try the devices by yourself on your own setup. I do not hesitate to buy any device that seems interesting. I try it, and I send it back to my resellers, if it does not satisfy me. And they refund me.
In France, it’s like that. The customer benefits of a trial period of a minimum of two weeks, during which he has the right to cancel the deal, to send the goods back to then reseller, and get a refund. Such is the law. Some resellers extend this trial period to a full month.
Those were objectively conducted evaluations which concluded that all of the external clocks tested bar one made matters worse. The other was no better with than without.
That’s hardly a glowing endorsement of external clocks.
I don’t need the feedback of others or to trust their opinions. The measurements speak for themselves.
Thank you, @ElTel , for your educational input.
If it was not a synchronization of the devices that produced an improvement, it’s something else that happened, and I ignore the reason.
I gave back the EtherRegen to the friend who lent it to me, and I don’t have it anymore. However, for me, the improvement with the Mastecr clock was not sufficient to justify the purchase of this switch.
@Graeme_Finlayson , you said something similar in the closed thread to @Torben_Rick , when he was asking for advises about the optical isolation. Nevertheless, he took the risk to spend €50, and got a nice SQ improvement. He opened a thread to report about it.
Anyway, there are different audiophile approaches. You try to prove something without listening. I’m also trying to understand the technological reasons, but when I listen I do it without apriorism.
When things work or do not work, we all try to find an explanation for the reasons. It does not mean that our reasoning was correct.
So let’s remain modest about our rational understanding of these matters.
At the highest level of manufacturing of audio gear, the components are tuned by ear, not by instruments nor measures. Even the best design engineers, and the finest measurements, can not guarantee that the sounding result is what people with good ears were looking for. During tuning, the desired results are achieved by trial and error. And there’s no way to understand or to explain what makes the audible difference.
That’s what I’m actually doing by tuning my own home system with my ear.
Agreed. If you would base recommendations on unbiased hearing only. We cheat ourselves when we know what we are expected to hear. Settled knowledge, proven in airtight scientific studies. Always try not to step into such traps. This is the simple trick when sales people offer multi week test periods for snake oil products. In the end our brain might overrule what we actually hear. Easy to avoid. Hear. Don’t look. Just hear. And then make a buying decision.
FYI, this is not a TCP/IP protocol it is a protocol that uses e.g. TCP/IP and the lower layers in the OSI model (layer 1-4) as all networked applications do.
If there were different TCP/IP protocols, other than IPv4 and IPv6, the internet would not work.
You refer to OSI layer 5, 6 and 7, resp. the Session, Presentation and Application layers.
There is a difference between routed protocols and routing protocols.
In short; RAAT is not a TCP/IP protocol and neither is Diretta.
You are correct. I wanted to say that the protocol of Diretta is based on TCP/IP, like the other streaming protocols that we know for long time and with which we are familiar.
English is a very difficult language, and it’s challenging for me to post in it, when I chat on forums.
No it is not based on TCP/IP, it uses or can use TCP/IP, but it can also use other transport and network protocols.
Just as it uses different Physical Layer “protocols” when traversing the ethernet.
TCP/IP is just the way information can find its way over a network, eg. the internet, nothing more nothing less.
Better phrased 
TCP/IP is just the way packets can find their way over a network, eg. the internet, nothing more nothing less.
As a principle of regulatory fact, it is not the case that advertising authorities consider objective and subjective assessments by manufacturers of the capabilities of their products to be equally valid. The UK’s Advertising Standards Authority (ASA) is typical:
As a point of ‘Substantiation’ under rule 3.7 ; “Before distributing or submitting a marketing communication for publication, marketers must hold documentary evidence to prove claims that consumers are likely to regard as objective and that are capable of objective substantiation. The ASA may regard claims as misleading in the absence of adequate substantiation.”
So, it is already the case that manufacturers cannot make unsubstantiated claims. The latest UK test case I could find was Tellurim Q, a high end audiophile cable manufacturer. This is why so much of subjective audiophile marketing must now be conducted indirectly via magazine and on-line reviews and social media influencers.
What the EU, ASA, FCA and other regulators are looking at is what limits to place on “proxy” unsubstantiated advertising by reviewers in both traditional and on-line media. I think what is interesting is where they will draw the line with unsubstantiated consumer opinion and social media influencers.
Sometimes things are now based on measurements, for example the Puritan stuff (see also audiosciencereview), that a lot of people including me initially held for snake oil. Maybe the first manufacturiers just didn’t know what they were doing, or the marketing department didn’t want to inform potential buyers.
I can hear differences with the Puritan stuff.
I heard differences between the Antipodes s30 and k50 musicservers, while on the same super high end equipment I couldn’t hear any difference between different ehernet cables. So these wires are real snake oil or jus for the golden ears only.
I posit that they’re just snake-oil. The -120dBFS 1 kHZ test tone was audible when amplified enough. If noise were a real issue, the tone would have been buried in the noise.
OnPuritan, see:
Puritan Audio PSM156 Review (AC Filter) | Audio Science Review (ASR) Forum
On Antipodes (and Taiko) see.
Archimago's Musings: As We Hear It: An audiophile comments on the Taiko Audio computer. The Mark Jenkins / Antipodes Audio Darko interview. On MoFi's One-Step DSD. And optical HDMI.
What exactly are you claiming?
I was claiming that a while ago many more people, like me, were on the side of the ‘digital is just ones and zeros and nothing else could matter. But other people in the industrie already knew that there was more going on than just zeros and ones.
I had to admit that I can hear clear differences between different streamers. If that would have been only my imagination, than I should also hear differences between two ethernet cables, even if they were exactly the same cable with a different appearing.
So at least for me, the audible differences between two ethernet cables were so small to my ears that it was not worth it to spend money there.
The audio science review is interesting because the Puritan clearly filters out noise but from a technical point of view it would be unlikely that this would help to bring the measurable noise in the Topping more down. So the Puritan is clearly “doing something” but they don’t know why someone with an outstanding preamp like the Topping would need that. Well, just have a listen then in your own system.
But how do they know this? Do they have some tests or measurements to confirm, or are they just basing the claim on perceived (i.e. subjective) impressions?
I don’t think it’s based on anything other than an intentionally deceiving application of analog principles to digital.