Yes, I use a Vovox Sonorus Power Chord on the Cisco 3560 switch. The Cisco has a built-in power supply and no external power supply can be connected. The Vovox is not an expensive cable (230 euros) and has brought an immediately audible improvement. It is worth a try.
I use the Cisco in the house as the first central switch for the entire network, including heating and solar panels with IGMP snooping. In front of the streamer (ND5XS2) I also use a Silent Angel Bonn F8 switch with Forester LPS power supply. It was specially developed for the Bonn F8 and has brought about the same improvement as the switch alone. I have not tried any different power supply units on the F8, but trust the supplier Silent Angel. I also recently tried a Vovox excelsus power chord as a supply cable for the Forrester power supply. I didnāt notice any great improvement spontaneously.
Yes DC cables have a profound effect. It surprised me too when I upgraded the DC power cable on my Plixir supply that feeds my Melco N100 from the standard one to the Plixir Statement cable. A huge improvement. Donāt quite know why this surprised me - every other cable makes a difference after all! Incidentally my Plixir Elite BDC PS is fed by a Naim Powerline, which in turn is fed from a Chord M6 block with a Cord Power Array plugged into it. The block is fed by a Chord Epic mains cable.
I agree the use of the cheap and nasty BT cable/plug assembly was far from ideal, but necessary since the correct size DC plug proved impossible to source. Believe me I tried very hard. I suspect that itās a proprietary size plug comissioned by BT to prevent this very situation, ie. people meddling with power supplies on their routers! The plug is apparently 5.5mm OD x 3mm ID (confirmed on a BT forum). There is a British company who make this size but it has a centre pin and the BT plug does not so will not fit (the input socket on the router has a centre pin). Apparently a plug of 6.3mm OD x 3mm ID will work and is easily available but itās a very tight fit so I donāt really like the idea of forcing the wrong size plug into the power socket on my router.
Interesting that you mention this. I was pondering doing just that with my BT router SMPS. Difficulties are correct DC plug impossible to source (as mentioned before) and the cable is captive on the wall-wart. So could the cable be cut very short, a length of audiophile DC cable be spliced in and the BT DC plug attached via a short length of its own cable? I donāt know. I think however that caution needs to be exercised here. The new cable will have different electrical characteristics. Could this affect the correct operation of the supply and the output filters? Iāve no idea.
looks like a tant but surrounded by mastick or something for whatever reason
But Nigel, actual network optimisation is hardly ever discussed by audiophiles on these sort of web sites and I suspect for 99% of customers is irrelevant and way beyond their understanding or means of doing anything about and this is for customers and dealers alike. However what is discussed ad nauseam is electrical and EM hygiene and mitigating common mode interfering currents etc in cablesā¦ and I believe quality dealers know about this. This equally applies to SPDIF, Ethernet, mains leads, interconnects and automation leads. I also think perhaps more emphasis should be put on room treatments and correct source signal grounding where makes are mixed and matched. In my experience, a system that has become over sensitised to tweaking where a slight tonal shift gives the appearance of significant more detail (you know references to night and day etc) is probably suffering from other issues such as bad acoustic performance in the listening position with excessive reflections or speaker phasing performance, especially in the mid frequencies, or common mode noise in connecting cables.
Another thread going on here links to Naim Steve harris where he mention SMPS and their noise.
Personally I use Roon RAAT to my various systems, but have Roon running on a Windows PC located elsewhere in the house to minimise switch mode PSUās etc. from the Hifi rack causing localised mains pollution. Sounds fine to me while I drink red wine 
Best wishes
Steve Harris
Software Director
Naim Audio Ltd.
100% Best advise is in that last line ā¦ā¦ caution.
My BT SH2 experiments have being limited to reducing switching noise on both DC & AC sides.
I have both the BT and Cisco switch SMPSās powered thru a UPS which contains a C+D mode filter & isolation transformer. The UPS powers the SMPS plug strip and its cable is heavily loaded with selected frequency ferrite mixes, plus the strip has a plugged in noise suppressor.
Each of the SMPS DC cables is also loaded with a very low frequency ferrite with each cable taking numbers of passes (turns) thru the ferrite core.
Using a small portable radio to detect noise shows whatever noise there was is now significantly reduced, the audio changes music voice and background is āimprovedā, which is all Iām saying as I was not prepared to take it all apart and back again.
@Nestor_Burma I agree, but never really considered a power cord upgrade for my switch.
@Wilfried my switch has a built-in power supply as well so a cable upgrade is surely an interesting option. I just wonder how much the sound could improve. When I compared it between the ethernet and the USB, I didnāt find a huge difference on my NDX 2. The USB had just a touch more definition and clarity, maybe.
@PJL a cable upgrade could be an interesting way to improve sound withouth changing the PS. One should try all steps in order to understand what really works for him, as far as I understand thereās no right or wrong answer in the end.
Interesting to read about your attempts at reducing noise. I was considering getting a Chord Ground Array device (RJ145 connection) to plug into either a spare switch port on the BT SH2 or into a spare port on my EE8. The BT Hub I suspect is probably the noisiest device so presumably the Ground Array would have maximum effect here.
At Ā£550 itās not exactly cheap, but then not silly money either. Hmmmā¦
I have tried, as far as possible, to keep tweaking to a minimum. My experience has been that systems that are very highly tweaked and optimised can sound incredible - BUT - this comes at a price, and not just a financial one. Such systems often exist on a sort of kife edge, a precarious state of balance, where the smallest upset to this can cause the entire performance to collapse. Itās like a āhouse of cardsā, with one tweak resting on another. Disturb a tweak (or card) at the bottom and the whole thing comes tumbling down.
Save your money, I very much doubt it will have any audible or measurable effect, some regard these mego expensive items as boxes of nothing, at best its fine tuning a system thats already fine tuned. Whatever YMMV
Yes, totally agree with that. This really is the issue unfortunately. There is no definite right or wrong way - it all comes down to trial and error. Which is fine if you can spare the cash to experiment and have the willpower and patience to do so.
Me, Iāve bought a PS which is useless to me as it sounds cr*p on my router. Thatās Ā£300 down the swanny. Iāll right it off as an experiment and learning experience but I canāt afford to repeat it.
Safest bet - stick with the manufacturer supplied PSās or follow their recommendations.
You can borrow them for nothing, so why not have a go and see what you think? I know of one member here who has a pair in his EE8.
If you are lucky enough, you can borrow cables and other gear from your dealer (unluckily I never had that luck!). Otherwise you have to buy and try. If I were you, Iād try to resell your PS and use the money for something else. Maybe you mentioned it before, but I wonder if your PS was run-in.
Yeah, that image is a good example of what Iām referring to when it comes to constantly tweaking. Big shiny expensive box must be better than little inexpensive box.
Yes thatās something I was considering. Having had a very positive experience with the Chord Power Array, which made a very noticeable improvement to things, I remain open minded about the Ground Arrays.
It will need to be a considerable improvement to justify an outlay of Ā£550. My thinking is that when I first tried a LPS on my router it sounded really very substantially better - presumably because of the reduced noise compared to the stock SMPS. As I described it then deteriorated and sounded rubbish. If plugging in a Ground Array reduces noise also then it may have a similar effect. If it does then thatās money well spent in my view.
Well the first time I tried it I left it for perhaps a couple of months or so before I re-instated the supplied BT SMPS - which now sounded very much superior.
Interestingly I read elsewhere of a guy that had put LPSās on all his network gear and thought it all sounded much better. After a few years for some reason he had to remove them and re-instated all the original SMPSās. Guess what? It now all sounded much better with these!
Something is definitely going on here - but I really donāt know what.
Thank you for the clarification, so your PS was well run-in.
Surely thereās something going on and itās somehow fascinating, Iām no expert and I donāt have enough knowledge/experience to judge that. Sometimes when things are too perfect on paper, they get dull and boring. If only there was a paper with good practices to optimize your network from an audiophile point of viewā¦ That would be a good starting point!
I doubt the BT super hub is materially noisy in a common mode way (relevant noise) as they incorporate VDSL modems, and VDSL is super sensitive to electrical RF noise if not to impact broadband synchronization speeds. They are possibly more sensitive than many typical hifi setups.
But with all home network equipment best keep away from sensitive audio components. Also best ensure your VDSL connections use proper twisted pair, including the connection to the modem. You might need to get a third party lead for that part. Your phone/broadband network connection wiring if fitted professionally will be using twisted pair. (Similar to Ethernet cabling)
He was probably bored of the sound and fancied something new, and then when he took them out again, heād got bored of the new sound and fancied something old. 
