Are my CAT5 and router my weak link?


I have paid a lot of money for my PS Audio PW DAC II with the bridge....as well as all of my interconnects, power cords and speaker cables. After all that, I have an inexpensive (relative to my system) wireless router that connects my computer to the PW DAC and CAT6 cables that are not too special. Are those components letting the signal come through fully? I am curious what others may have done.

Thanks
Jeff
jeffatus
Personnally I believe that you are transmitting data and that the DAC and Router are probably designed to work with mediocre wire. Although I see that some companies such as AudioQuest are offering high-end cabling for ethernet and Cat7. So maybe they have found some performance advantage or just an extension of another profit center. But years ago we thought an interconnect was just an interconnect and the power cord was just a power cord. Someday I wonder if we will see some type of air ionizer that we can filter the air in our listening room to enhance the effortless flow of soundwaves between the driver and the ear. I just hope it is quiet!
Jeffatus, Time jitter is the only thing that affects sound of digital transmission. Wireless or Ethernet data is just that - a data. It means it is being sent in packets without timing. Bad Ethernet cable or wireless router can cause disruption is data delivery resulting in dropouts but cannot change the sound.
Kijanki is correct.
I do this everyday it's part of my job. Not to worry unless your connections are sub par(defective) you will not have a problem.
Oh, I'll likely regret this post. I know digits are digits and data is data. But I can clearly here differences in clock cables between my clock and the transport/dac. It is not subtle. My wife can hear it. The stock cables aren't cheap/trashy at all. The other clock cables are a Cardas Lightning 15/Purist Proteus Provectus Praesto.

I can even hear the Purist being more transparent and giving the sound more focus/palpability vs the Cardas.

So something is going on here vs just transmitting the data...

I did try a Audioquest firewire from my transport to dac...again, you can quickly hear this also...
Any cable that is conducting high speed digital signals, such as the OP's CAT6 ethernet cable, firewire cables, USB cables, etc., and that is located in physical proximity to the audio system (e.g., in the same room), can radiate or couple RFI (radio frequency interference) into the audio system, with effects that although unpredictable could conceivably be both sonically significant and cable-dependent.

Cables that are conducting signals that are involved in the timing of D/A conversion, such as (apparently) the clock cables Jfrech is referring to, can of course be expected to be much more critical, as a result of noise pickup, ground loop, and impedance matching issues that can affect jitter.

If the CAT6 ethernet cable the OP referred to is in the same room as the audio system, he may wish to consider experimenting with inexpensive shielded ethernet cables, as member Bryoncunningham described doing in this thread. See the posts in that thread dated on and around 2-16-12. Inexpensive ethernet cables are commonly unshielded, but good quality shielded cables are also readily available at low prices.

Regards,
-- Al
I work with this every day. Shielded cat 5/6 cables test with LOWER bandwith than the unshielded types. I have installed and tested thousands of miles of this cable and the only time I have used shielded in in severely compramized locations like radio stations with broadcast antennas on site. The shield compramises the magnetic field genenrated by the twist of cat 5/6 by phycally restricting it within the shield. Each pair of wired(4Prs.) is twisted at different ratios per inch to generate specific magnetic fields to control cross talk and give excellent speed. The shield is always a compramise in the data world. I have even had to replace shielded with unshielded. The whole idea of the twist is to negate the need for a shield.
Tubeking, I agree with everything you said. However, I question its relevance. The concern you appear to be addressing is successful communication of ethernet data, apparently over relatively long distances. The concern I was addressing is radiation FROM the cable into arbitrary circuit points in the audio system. Everything else being equal, that can be expected to be REDUCED if cable bandwidth is LOWER. Lower bandwidth = slower risetimes and falltimes = less RFI, everything else being equal.

Also, note that I did not say that results would NECESSARILY be better with the shielded cable. What I suggested is that it may be a worthwhile (and also very inexpensive) experiment. Which certainly turned out to be the case, per the thread I had linked to, in the system of someone who IMO is one of our most credible members.

Regards,
-- Al
I can confirm what Al has reported about my experiences when I replaced an unshielded Cat 5 cable with a shielded Cat 6 cable. The result was more resolution. A lot more.

The $7 shielded Cat 6 cable resulted in a bigger improvement in SQ than several $1,000 power cords and several $2,000 interconnects. Yes, I know that sounds crazy. I can't explain it.

I'm not saying that other systems will benefit similarly. In fact, I doubt it. But it's certainly an affordable experiment.

As far as the router goes, I too have a router indirectly connected to my audio system (outside line -> 15' shielded Cat 6 -> router -> 1' shielded Cat 6 -> ethernet switch #1 -> 20' shielded Cat 6 -> ethernet switch #2 -> Sonos -> audio system). Ethernet switch #2 is a bus between the computer and the Sonos. Ethernet switch #1 has only one function: to sever the connection between the router and the audio system...

The router is left on all the time. I have the PSU for ethernet switch #1 plugged into a rocker switch, which is itself plugged into the wall. When I listen to music, I flip the rocker switch to kill the power to ethernet switch #1, which kills the connection between the router and the audio system. Don't know if any of that is relevant to your setup, but it's another easy and affordable thing to try.

Bryon
If I understand it correctly Ethernet cable connects computer to wireless router. If that's the case then it is in some distance from the DAC that has built in wireless receiver eliminating capacitive coupling and leaving electromagnetic radiation to consider. This radiation is practically eliminated, not only by very tight (>2twists/cm) twist on CAT6 cable, but also the fact that signal is balanced. Radiation is limited to common mode noise coming from the system (perhaps power supplies). This noise (whatever the source is) has to be strong and at least 30MHz to make effective (1/10 wave) receiving antenna of typical 1m interconnect. At this frequency skin effect is very strong and interconnect's shield is working very well (Noise from crude computer switchers is in the frequency approx. 100kHz and has no chance to be received by 1m antenna). Of course it would be wise to keep this Ethernet CAT6 cable as short as possible and far from the DAC.
Think of it like this. Your data is transfered from a NAS into a buffer in the PWD Bridge. If you copy an excel file from a NAS to another node on the network, it will be bit for bit perfect (i.e. the exact same bits) all the time, irrespective of quality of your cable. The same applies to your music file. It gets tricky when timing information is involved - not the case here. The bridge is completely asynchronous.
Kijanki - Your expertise in this area far exceeds my own. There may be good technical reasons to doubt that an ethernet cable can affect sound quality. Nevertheless, the effect I heard when I replaced an unshielded Cat 5 with a shielded Cat 6 was, from my point of view, too obvious to be attributed to placebo.

When a listener reports an experience that challenges an accepted explanation, it raises the question of the reliability of the listener. But it also raises the question of the reliability of the explanation.

Bryon
Using wireless LAN connection (Wifi) provides the best solution for physically isolating sensitive audio playback gear from potentially noisy computer gear as an insurance policy for best results. I would recommend everyone use this approach to connect their computer gear to their stereos and rest easy at night.
Bryon, Your case might be different. Perhaps Ethernet cable was in close proximity to analog wiring (interconnect or speaker) or I'm just plain wrong about it (I was wrong once in 1960). Audio is not exact science and I'm just trying to understand. Maybe balanced drivers are never exactly symmetrical and there is some high frequency component. It is possible that computer you used produced high frequency common mode noise. I hope Al will help with this.

Mapman, I Agree 100%. Not only that computers are noisy but also can and should serve its main function and therefore its location might be remote (mine is across the room). I use my computer during music playback because I know that it cannot change timing on the DAC side. For the same reason I use free Itunes, cheap computer, not a lot of memory, standard external hard disk etc. SIMPLICITY.
Hi Kijanki,

Bryon's situation is indeed different in several significant ways. One being that there is no wireless link between the cable in question and the system. However, following conversion of the ethernet data to S/PDIF, which is performed by a Sonos, the S/PDIF data goes through a high quality re-clocker, that also provides galvanic isolation, before it is input to the processor in which D/A conversion is performed.

I am in general agreement with all of the technical comments in your posts above, except that I would emphasize that matters of degree are involved. And the matters of degree have no clearly definable threshold separating what may be significant from what is insignificant. For instance, concerning your comment that:
This noise (whatever the source is) has to be strong and at least 30MHz to make effective (1/10 wave) receiving antenna of typical 1m interconnect.
While the 1/10th wavelength criterion is a reasonable guideline to use in many contexts, I would be hesitant to declare that in the context of an audio system an antenna that is less than 1/10th of a wavelength will be sufficiently INEFFECTIVE to reduce noise pickup to insignificance. Especially when sub-nanosecond jitter effects are presumably significant at the point where D/A conversion is performed. And given also that low-level RF may significantly affect the performance of analog circuitry. There is yet another thread that has recently appeared about someone hearing radio stations while listening to a phono source!.

Also, in addition to the possible antenna effects of interconnects and speaker cables (with RFI picked up by speaker cables perhaps becoming audibly significant as a result of entering amplifier feedback loops), I would not rule out the possibility that RFI picked up in AC power wiring may find its way to circuit points in the components where it could have audible consequences.

Concerning the 1/10th wavelength guideline specifically, I'll mention that some of my antique AM radios, that are designed to work with external antennas and do not include built-in antennas, will receive non-local stations on even the lower part of the AM band, with good quality, using a piece of plain hookup wire just a few feet long as an antenna. In those cases the antenna is well under 1/100th of a wavelength. And some of those radios, that do not have well-shielded RF and IF sections, can pick up those stations with no antenna connected at all.

Concerning the RFI reduction resulting from twisting of the conductors carrying balanced signal pairs, while obviously that reduction will be very substantial, it too is a matter of degree, and will not be perfect. How imperfect will it be, at each of the many frequencies that may be involved, and how much imperfection has to be present before there may be audible consequences? Obviously I have no idea. But my point is simply that if the OP's ethernet cable is located in relative proximity to the audio system, the possibility that changing the cable to a shielded type could make a difference for the better does not seem to me to be beyond the bounds of plausibility.

Best regards,
-- Al
Al, Thank you. I often tend to think in absolute terms while boundaries in reality are not that sharp. Tubeking sugested that shielding might compromise twist density making it worse instead of better. It is easy enough to compare since Ethernet cables are not expensive. I would use shortest possible cable as far as possible (since field drops rapidly (inverse square) with the distance. I would also avoid setting router at full power in close proximity if there is no need for that (no dropouts).

Do shielded cables require special connectors? I thought that plug has 8 pins (4 twisted pairs) with no room for the ground. Ground would have to somehow clip to chassis.
Do shielded cables require special connectors? I thought that plug has 8 pins (4 twisted pairs) with no room for the ground. Ground would have to somehow clip to chassis.
Hi Kijanki,

Excellent question. The connectors on all of the shielded ethernet cables that I have seen have metallic housings, that are presumably connected to the shield. And when inserted into the ethernet connector on all of the computers I am familiar with, that housing will contact a metallic tab which is in turn grounded to the chassis.

Best regards,
-- Al
I had my PWD system wired with CAT 5. It sounded good. Then I started adding CAT 6 with each piece it sounded better. I thought I was done. Then I saw CAT 7 on Amazon. I tried a piece or two. Drat it sounded better. Now I'm slowly replacing every thing with CAT 7. Anyone need some wire?
I am jumping ship when CAT10 hits the market. Meanwhile, am am sorting out the directionality of my fuses.
08-07-12: Sgr
...I saw CAT 7 on Amazon. I tried a piece or two. Drat it sounded better.
This comment made me buy some CAT 7. Today I changed the 50 foot run between my computer and my ethernet switch. I replaced shielded CAT 6 with CAT 7.

To begin with, it improved my internet speed by about 3Mbps. Theory? Maybe...

Better shielding = less RFI/EMI = fewer errors = fewer resends = faster speed.

Also, it sounds better. More resolution. More relaxed at high volume. Too audible to be placebo, IMO. Maybe...

Better shielding = less RFI/EMI = ??? = less jitter.

Don't know what "???" is.

Bryon
???=less digital cable and system noise since they both produce jitter. Also less analog cables pickup. One thing to remember is that speed of Ethernet cable directly doesn't effect anything since data has no timing. Effect is indirect by radiating noise.
I switched my freebie network cables over and heard a difference. One was clearly preferable to the others. So I demoed an Opal, was a sure improvement on all the freebie ones, so much so, I paid the £100 for it...

Yes maybe mad, but it was cheaper than mains cables, IC's and speaker cables I have...
Thanks for the responses so far. It has made for interesting reading. I have my computer hard drive connected to the router via cat6 cable, non shielded. That run is about 10 feet. Then I have a 50 foot run, cat6 unshielded, from the router to the DAC.

It sounds like a relatively inexpensive experiment to try the shielded runs, but what about the router? I just keep thinking about all of the money I have spent for high end gear and their fancy connectors, etc. and want to know if a $120 router will be my weak link.

Thanks!
Jeff
Try a linear supply for the router..
I have two d-link boxes both now with linear psu's, made a small but noticable improvement.

The installation of just one MeiCord Opal cable made a nice improvement.

Now finding out the above affects sound repro, I'm hoping to run a dedicated pc with my Meicord just for music, cutting out the d-link boxes and two cat cable runs.

You may find this interesting:
http://soundcheck-audio.blogspot.co.uk/2011/11/touch-toolbox-hw-and-network.html
I just keep thinking about all of the money I have spent for high end gear and their fancy connectors, etc. and want to know if a $120 router will be my weak link.
I doubt it. The physical separation between the router and the system would seem to make it very unlikely that RFI generated by the router would have any audible effects on the system. It is conceivable to me that differences in the risetimes and falltimes of the signals generated by different routers could result in VERY minor differences in noise conditions within the DAC, but I doubt that those differences would have audible consequences. Even if they did, there would be no reason to expect a more expensive router to necessarily be better in that respect, and it very conceivably could be worse.

Regards,
-- Al
Bryoncunningham.
Glad you liked the CAT 7!
It's funny although cables aren't supposed to make a difference the CAT 7 do. Funny my PS Audio PWD system has functioned better and better each time I jumped from CAT 5,6 and now 7. I have no explanation why. All the cable Gods here will never admit that it does.
In my own setup, I use an Ethernet Opto-Isolator that sits between the ethernet cable that feeds my "sterile" PC and the router that the cable connects to.

This device stops any electrical noise from traveling thru the copper conductors of the ethernet cable before it gets to my music server. Same concept as installing a dedicated circuit for your audio equipment, but for the LAN connection.

All the cheapo routers, NAS drives, ethernet printers..etc found in the home environment have no need to perform their function in a silent manner nor where they designed to do so. If you start to add up just the Wall Wart switching power supplies alone in the path between your PC and your DAC you begin to see an ugly picture form. Certainly the PC needs no additional help when it comes to generating noise so I feel anything you can do to help isolate it from the rest of this crud is a bonus.

Granted, the number of configuration choices one could pick from to setup a music server are fairly broad so some may be more affected by said noise than others and if you have done nothing at the PC level to help lower its own noise than all of the above may not matter anyway.

In my own setup I use a low power ALIX computer running Voyage Linux which only requires about 12 watts of power to perform its duties. I feed the ALIX computer power via an adjustable laboratory grade linear DC power supply. In my case this Opto-Isolator makes sense as the music server is already pretty clean from noise so any additional filtering is a plus. My DAC is also optically isolated from the Alix computer over its USB port Input (Ayre QB9).
08-12-12: Jeffatus
I have my computer hard drive connected to the router via cat6 cable, non shielded. That run is about 10 feet. Then I have a 50 foot run, cat6 unshielded, from the router to the DAC.

It sounds like a relatively inexpensive experiment to try the shielded runs, but what about the router? I just keep thinking about all of the money I have spent for high end gear and their fancy connectors, etc. and want to know if a $120 router will be my weak link.
I'm hesitant to contradict Al's opinion, since he's eminently qualified in these kinds of technical matters, while I am not.

Having said that, I suspect it's possible that your router is degrading SQ. I would consider two experiments...

1. Replace your unshielded Cat 6 with either shielded Cat 6 or Cat 7 (always shielded by specification). Cost = about $25.

2. Remove your router from the system, run a direct ethernet line (preferably shielded) between your computer and your dac, and see if it sounds better. If it does, but you need the router for functionality, you can either...

(a) use the router wirelessly, so that there is no hard line between it and the computer, or...

(b) add a simple ethernet switch downstream from your router. So the arrangement would be...

computer -> 1' Cat 6/7 to ethernet switch...

...ethernet switch -> 10' Cat 6/7 to router
...ethernet switch -> 60' Cat 6/7 to dac

If you added all new cables and an ethernet switch, cost = around $65.

As I mentioned above, I experienecd significant improvements in SQ when I went from unshielded Cat 5 to shielded Cat 6 and then more improvements going from Cat 6 to Cat 7.

As for the router, in my current arrangement, I have two ethernet switches in the configuration, so that when I listen to music, I can kill the power (with a simple rocker switch) to the ethernet switch closest to the router, which severs the hard line between the router and the audio system.

You may just wonder why I don't just shut off the router. The reason is that I don't want to interrupt the other wireless devices in the house from communicating with it, and I don't want to wait for a long reboot when it turns back on. With the ethernet "kill switch," the reboot is about 5 seconds and there are no settings to be lost/changed, so it's idiotproof. Good thing for me.

Bryon
Eniac26,
So what is the brand of the opto isolator and where can I buy one?
Thanks in advance!

Steve
Interesting Bryon, I am trying to work this out in my head.....

I need the wireless router on because my iPad controls the computer wirelessly. The computer, via PS Audio's eLyric, then sends the data to the Perfectwave DAC.

So.....

Computer to the switch via CAT7.

From the switch: one cat5 to the router, one cat7 to the DAC

Then modem will still be connected to the router....then to the switch....then to the computer.

I am basically just adding a switch between the router and computer, while bypassing the router from the computer to the DAC....via the switch. I need to draw this out before my brain explodes! Hahaha

Jeff
Jeff, you've got it right, except that it would probably be a good idea to upgrade the router-to-switch cable, in addition to the others. Although that cable will no longer be in the signal path between the computer and DAC, it could still conceivably radiate or couple digital noise into pathways that ultimately lead to the DAC, or even to other parts of the system.

Considering the low cost that is involved, Bryon's suggestion of the switch seems worth trying, although whether or not it will make a difference for the better is anyone's guess. Among many other things, it would depend on how the characteristics of digital noise generated by the switch may differ from the characteristics of noise generated by the router; on the degree to which router-generated noise can propagate through the switch; how the risetimes and falltimes of the output signals of the router and of the switch compare; and on the sensitivity of the DAC to all of these things, if indeed it has any sensitivity to them at all.

Regards,
-- Al
08-14-12: Jeffatus
The modem will still be connected to the router....then to the switch....then to the computer.

I am basically just adding a switch between the router and computer, while bypassing the router from the computer to the DAC....via the switch.
That's right, Jeff. But Al is correct when he says...
...Bryon's suggestion of the switch seems worth trying, although whether or not it will make a difference for the better is anyone's guess. Among many other things, it would depend on how the characteristics of digital noise generated by the switch may differ from the characteristics of noise generated by the router; on the degree to which router-generated noise can propagate through the switch; how the risetimes and falltimes of the output signals of the router and of the switch compare; and on the sensitivity of the DAC to all of these things, if indeed it has any sensitivity to them at all.
That is why I would add a SECOND ethernet switch. Yes, I know, I'm sounding crazy. But bear with me...

If you add a second ethernet switch, you can kill the power to the second switch and SEVER the ethernet connection between the router and the computer/system. I drew you a picture, which you can see here.

That is the configuration I'm currently using. When I listen to music, I kill the power to ethernet switch #2, cutting off the ethernet connection between the router and the system. That way...

1. The router remains on all the time.
2. The router is disconnected from the system when listening to music, and reconnected to the system with the flip of a switch (pun intended).

How does your brain feel now? :-)

Bryon
Hi Bryon,

Note, however, the statement in Jeff's most recent post that:
I need the wireless router on because my iPad controls the computer wirelessly. The computer, via PS Audio's eLyric, then sends the data to the Perfectwave DAC.
So if I understand correctly, in his particular situation the connection between the router and the computer needs to be maintained during music playback.

Best,
-- Al
Oops. I missed that. Then what about connecting the router to the computer wirelessly, Jeff?

bc
Huh.....

Well, I wonder if I make the computer connection to router wireless

Then

Connect the computer direct to the DAC (bypassing the switch altogether)

I can't think of any reason I need a switch for the computer to talk with the DAC. As long as the PW DAC can still get the album art, which is not a deal breaker, then I can't think of why it wouldn't work.

The eLyric controller on the iPad would send the controls/commands wireless to the router, then the router sends it wireless to the computer, which then processes the request and sends the info direct to the DAC via CAT7 cable. I keep thinking that the DAC does more than process the audio signal and album artwork, but I think it's the computer that does all the work. The DAC just processes the data.

Very enlightening, I never would have thought of that! Does anyone see anything I missed?

Jeff
I am using Cat 7 cables throughout. They cost just a little bit more but they appear to be more robust in the connections.
To SGR,

I purchased my Opto-Isolator from Black Box (linked below). I am using the 100MB unit as it offers more than enough bandwidth for audio purposes but they do sell GB ones also.

http://www.blackbox.com/Store/Detail.aspx/Ethernet-Data-Isolator-10BASE-T-100BASE-TX/SP426A

By using one of these Isolators you are eliminating any noise from propagating beyond the point of its location. There is no need to rewire your LAN again.

For our purposes (Audio) CAT5 is more than sufficient in this configuration (with Isolator) because at the end of the day these other cables are offering nothing more than additional shielding from interference. The ones and zeros could care less about this interference unless its so severe as to cause them to no longer be the same ones and zeros at which point you obviously have other issues to worry about.

I have done some fairly through testing of this unit prior to using it in my own setup and found no difference in data transfer rates or ping times with the device Inline/Not Inline. I also conducted CRC Checksum testing of data that passed thru the Isolator verses the same data that was copied without the Isolator and found it was 100% the same in both cases.
08-14-12: Jeffatus
Well, I wonder if I make the computer connection to router wireless, then connect the computer direct to the DAC (bypassing the switch altogether).... Does anyone see anything I missed?
That's a good question, given that it sounds like the computer is either a laptop or a desktop with a wireless adapter. Here are a couple of points to consider, though:

1)In doing that essentially what you would be doing is substituting one significant generator of digital noise (the computer) for another (the router). And quite possibly the computer is considerably worse in that respect than the router. Having a network switch between the computer and the DAC could conceivably still provide significant noise reduction benefit, with respect to computer-generated noise in this instance.

2)Changing to a wireless connection between the router and the computer might slow down your internet connection speed, depending on the speeds of the internet connection and the wireless link. If you frequently have occasion to download large files that might be a significant consideration.

Regards,
-- Al
Jeff - Sorry this has become a bit complicated. Al is making a lot of good points. IMO, many of the possibilities he's raised suggest that you should experiment. Some of the experiments we've discussed are free and the others are relatively inexpensive.

IME, computer audio is filled with mysteries and magic. So sometimes it's difficult to know the best approach without experimentation. Hopefully, you'll find it fun.

Keep in mind also that you are likely to get good results with any of the approaches we've discussed, in light of the fact that you have an excellent dac. So we're really talking about the last few % of sound quality.

If you do nothing else, use Cat 7 for the hard lines. If you decide to experiment, keep us posted with the results.

Bryon
Well said, Bryon.

Best,
-- Al
Eniac, thanks for providing the info about the opto-isolator, which certainly seems like something that could be beneficial in many setups, and that apparently has no downside aside from its cost.

However, while it figures to be something that would eliminate groundloop-related noise, without further technical information on it (which I couldn't find via a Google search) I'm uncertain as to the degree of effectiveness it would have with respect to source-generated noise that may be riding on its input signal. For instance, some amount of stray capacitance will exist between the electrical parts of the device, that may to some degree allow noise to bypass the opto-coupler device. Also, I note that its intended purpose is described as surge protection.

Also, I would not necessarily conclude that it would make cable upgrade redundant, because the existing unshielded cables could conceivably radiate noise that would bypass the device. That could occur by radiation into the power wiring, or directly into system components or cabling. Bryon's experimental results would seem to support those possibilities.

Regards,
-- Al
Eniac,
Did you notice any difference in SQ?
If so what?
Hello Al, thanks for your response. The only detail I could dig up about this devices ability to reject current leakage across the optical isolation barrier was found in an article pertaining to the European Medical Device Directive (EN6060-1) which this product is said to comply with.

If your real bored and feel like reading it I have linked to the document below which talks about the allowable current leakage given a certain air gap distance which I can only assume this device complies with. From what I saw, the European standard allows for .5mA worth of Earth leakage & a .1mA enclosure leakage under normal conditions. Double that during an "Event".

Article can be found here:
http://www.newark.com/pdfs/techarticles/xpPower/MedicalPowerSupplies.pdf

SGR, In terms of the SQ differences I heard before and after the installation of the device I'm afraid that in my setup I heard no change under normal day to day listening.

I think I could here a slight difference under critical listening sessions (more air around the performers within the soundstage) but certainly not enough to convince any DBT subject.

Please keep in mind that in my setup previously described I have already gone to great lengths to minimize the propagation of noise via the LAN cables as much as possible even before the purchase of this device. In someone else's system the SQ differences may be far greater than my own if they haven't taken all the same precautions. One example of these precautions would be that I maintain at least a 3ft gap of separation between all of my various networking equipment and non of which share the same electrical outlet. This alone helps with any one noisy device from polluting the other which could ultimately compound the amount noise radiating thru or traversing down the Ethernet conductors toward your audio system.
Eniac, thanks for providing the link, which I read through. It doesn't seem particularly relevant, though, as what it is addressing is leakage current that occurs in response to the AC line voltage, at the AC line frequency. The concern here, of course, being mainly digital noise at very high frequencies. Also, since this device does not utilize any AC power, I suspect that its qualification against the EMDD is pretty much a formality, at least with respect to leakage considerations. Finally, I note the statement that:
Reducing leakage current within a power supply usually means eliminating or limiting the value of Class Y filter capacitors from live-to-earth and neutral-to-earth. It also demands that stray capacitance to earth is minimised through careful design. Unfortunately, the overall effect of these measures tends to compromise EMC performance, although minimising stray capacitance can reduce common mode noise.
So in the kinds of designs being discussed in the paper there can be a tradeoff between minimization of AC leakage and optimization of EMC (Electro-Magnetic Compatibility, referring to the effects of radiated interference).

That said, as I indicated earlier the device does seem like something that can be beneficial in some systems, and that has no apparent downside apart from cost. Thanks again.

Regards,
-- Al