Well, I have the Vivaldi DAC, Upsampler, and Clock, and a Cybershaft OP21A reference clock. My apologies for the length of this reply. The TL;DR version is in bold below. I’ve done 4 things to the network ahead of the Upsampler:
1. Standardized on unshielded and certified Cat6 cable (per dCS recommendations). I’ve tried a few “audiophile” Ethernet cables and concluded that my life expectancy did not justify that rabbit hole any more. Further, while I believe in the old aphorism “everything matters,” and that includes cables in the digital realm, I believe the “everything” that matters in Ethernet cables is that certification on which one can rely and expect the cable to perform as intended, and as all applicable “participants” [from the designers of the spec to makers of the equipment we use] expect it to behave. I believe a poorly designed or made cable can affect the intended performance, but I do not believe that a properly designed/made/certified cable can act as a tone control or a device to recover additional data about the recording (e.g., soundstage, imaging, depth, etc.) that is otherwise lost by another properly designed/made certified/cable. In theory, an improperly designed/made cable could add something to the signal. (e.g., a variety of different types of noise, but I am still struggling with how an Ethernet cable could deliver more bass or less treble as I have read in some (IMHO only) frankly nonsensical reviews. So, having tried a number of different cables to check against my own expectation bias, I have consistently returned to my standard from Blue Jeans Cable. (I use fiber for a couple of long runs between my primary switch and the switch I am about to describe.)
2. For my speaker and headphone systems, I use a Cisco 3560 switch. These are enterprise switches, with much better PSUs, and audibly lower noise than the (not cheap) SG300 switches that I had previously. I learned about these switches, IIRC, over at the Naim and Audiophile Style forums (along with the 2960 series). Their performance is not based on audiphoo. They aren’t cheap new, but they’re readily available refurbed for very reasonable prices. I have tried so-called “audiophile switches,” and have heard zero audible improvement over the Cisco 3560. In fact, with one exception, they generally sound worse (albeit only by small degree).
3. Between each switch and the DAC or Upsampler, I use a DJM GigaFoil4 filter. What I like about the GF4 is that it essentially incorporates in one box what otherwise requires two Fiber Media Converters, two PSUs, and a short length of fiber, which is what I used to have between each DAC and switch. Even though the GF4 is supplied with an LPS, I power each GF4 with the 5V/1A output of a Keces P8 LPS. [BTW, props to Lumin for including a fiber input on their X1; I hope Vivaldi’s successor is similarly endowed.]
4. Finally, I am currently re-testing the UpTone Audio EtherREGEN. When I first tried the ER, I did not think it afforded any improvement compared to the GF4. Still, I did not return it to UpTone (which has a very reasonable return policy), thinking that I might try it again at some point. I so stated in more than one forum, including here. I also expressed a fair degree of circumspection about the validity of utility of clocking the ER. Back in late April or early May, Alex Crespi of UpTone called me at home, and asked if I was willing to discuss these assessments. I was more than happy to. We spoke for over an hour. I agreed to re-read the “white paper” on their site (which I had previously read), and to re-listen to my system with the ER in it and clocked by the Cybershaft. I’ve been doing that for about three weeks now. And I am beginning to wonder if the damn thing doesn’t make a difference.
I am well aware of the shortcomings of sighted testing, and I know the arguments about the various types of listening comparisons, expectation bias, and confirmation bias, as well as “brain-burn” (which I find more persuasive than a lot of the hooey I read). What I have found works for me is extended listening (much more fun that frequent swapping of stuff like cables or network devices), keeping notes, and occasionally asking my non-audiosilly wife how the music sounds to her. Once in a while, a change will be immediately apparent (clocking or Torus power supply). Other times, it will take more time to perceive that something has changed (Cisco switch or Iconoclast Gen 2 cables). I will continue to listen to the EtherREGEN. I am well aware that objecvtivists tend to be dismissive of it, because of the lack of verifiable measurements in support of some of its claimed effects. The ER is a fully functional switch, and it costs much less than other so-called “audiophile switches,” though it has fewer ports; but I would like to see something that explains why it should/does sound different, or contributes to my Upsampler/DAC sounding different. And I am hopeful that UpTone’s John Swenson will in fact publish measurement data to back up the claims (I like to understand the engineering, when I can; ergo BJC and Iconoclast, for example); their white paper has a lot of words, but UpTone acknowledges that it’s short on measurements. Until then, I will keep listening. The ER does no harm in my system, and I am open to the possibility that my system sounds incrementally better with the ER in it.