I've bought an ifi Audio iPower SMPS for my Netgear GS105v4 switch.
With its active noise cancellation & 12 element output array its claimed the iPower SMPS has an exceptionally low noise floor @ ~1uV, compared to a low noise linear power supply with ~20uV & a consumer grade SMPS that's typically 1000uV.
My present LAN set up is a bit OTT w.r.t. to suppressing RFI, switching & other random electrical noises; I've tried to reduce it as much as possible with screened cables, ferrite & correct LAN grounding.
The power to the LAN switch SMPS is via an APC 350 UPS that includes an isolation transformer & common mode choke. Its plugged into a four way power strip together phone & broadband SMPS's & a Russ Andrews Silencer, the short power strip cable has a ferrite clamp on each end. I have assumed the UPS isolation transformer & choke, plus the clamp & ferrite should go some way to reduce the power supply switching noise feeding back into mains power. This new SMPS is intended to reduce noise on DC power to the Netgear GS105v4 switch.
Measuring the iPower in comparison to the Netgear SMPS showed the Netgear voltage varied & the iPower was very stable to >0.01VDC. I also used my little hand held 'scope & that was not able to show much more than the voltmeter other than see a mV-AC element, but am not sure what that is showing other than question the iFi claim of better than 1uV noise floor.
I first measured VDC & Hz with no load & then loaded the output with a 22ohm resistor, that's 6.5watt & 63% more than the Netgear switch max.
iPower
No Load – 12.22VDC 6 .6mVAC 0Hz
6.5w Load - 12.18VDC 6.6mVAC 0Hz
Netgear
No Load - 12.14/12.16VDC 9.9/15.3mVAC Hz started as 50Hz & settled at 0Hz
6.5w Load - 11.70/11.78VDC 10.1/18.2mVAC 0Hz
OK that's the numbers, what about the SQ.
First impression is something has changed, not at all sure what, its subtle & not easy to define other than its different. It will probably need a few hours concentrated listening, so I will do that this evening & post again tomorrow.
Posted on: 13 January 2016 by nigelb
Thanks Mike, very informative.
As I am a mechanical engineer rather than an electrical one , I am not sure what the comparative (iPower vs Netgear PS) figures mean. Do these mean the iPower is performing in a more stable manner or are these differences insignificant?
As you indicate however, it is the difference in SQ that really matters and clearly these differences are subtle and you need more time to evaluate them. I look forward to hearing your considered view on the iPower.
Cheers
N
Posted on: 13 January 2016 by Mike-B
As I am a mechanical engineer rather than an electrical one , I am not sure what the comparative (iPower vs Netgear PS) figures mean. Do these mean the iPower is performing in a more stable manner or are these differences insignificant?
As you indicate however, it is the difference in SQ that really matters and clearly these differences are subtle and you need more time to evaluate them. I look forward to hearing your considered view on the iPower.
Hi N, I see the stability in the Netgear unit as indicative of the possibility of lower quality especially in the VR section & the voltage drop under load as possibly working near its limits.
Yes SQ is the all important end, problem is I trust my voltmeter more than my ears 
Posted on: 13 January 2016 by Mike-B
Mike fibre is fairly straightforward - but as the NDX uses electrical interfaces - you still have to have an 100/1000BaseTX switch or transceiver to contend with - and course these can create noise..
........ thats what I meant by " & I understand its not quite that simple".
At some point we all get arrive at the far enough zone, I'm close to that now.
If I can convince myself that I have minimal noise on my ethernet LAN, that's it.
Posted on: 13 January 2016 by Mike-B
I will be following this thread,but a quick question.
Are we talking switch only smps for improvements or also nas and router?.
scott
For me its a toe dip & look-see into the switch SMPS, at this time I have no suspicion that NAS (especially) or router is adding noise. If & when I find it/they are, then I will go look again. Regarding NAS, a Lin owning friend with the same NAS make as mine, bought a LPS that cost almost as much as the NAS, he is particularly disappointed as he hears no change, so will need some persuading.
Posted on: 13 January 2016 by Simon-in-Suffolk
Mike fibre is fairly straightforward - but as the NDX uses electrical interfaces - you still have to have an 100/1000BaseTX switch or transceiver to contend with - and course these can create noise..
........ thats what I meant by " & I understand its not quite that simple".
At some point we all get arrive at the far enough zone, I'm close to that now.
If I can convince myself that I have minimal noise on my ethernet LAN, that's it.
Mike, the way to measure noise and confirm you have minimal noise on your LAN Ethernet leads is to place an EM / RF meter by them... I suspect you might be shooting in the dark a little bit with out it..
Regarding fibre, I mis understood you, I though you might have been referring to the different fibre types and adapters (OM1,2,3,4) and their optimum frequencies and distances.. That can catch you out.. Or at least it has me me in my professional capacity.
Posted on: 13 January 2016 by Mike-B
.......................
.................. Measuring the iPower in comparison to the Netgear SMPS showed the Netgear voltage varied & the iPower was very stable to >0.01VDC.
OK that's the numbers, what about the SQ.
First impression is something has changed, not at all sure what, its subtle & not easy to define other than its different.
Second impression is yes something has changed, its subtle in some areas, others like clarity & naturalness is more obvious.
The presentation seems to have gained clarity & is lighter & smoother. Bass, mid & treble seem to be more detailed & in some respects more noticeable. In the better detail is a more natural feel particularly with voice & acoustic instruments, most noticeable is well recorded piano. Sound stage seems wider, more space & soloist are more forward.
I'm not sure how well suppressed or to what effect the Netgear SMPS had on the sound, as Simon says I need to go sniffing with an EM/RF meter to answer that question, but unless I can blag one for a few days, I'm not going there. This new one seems to have tidied up the sound & whatever its a keeper, if nothing else the very stable voltage control & practically no change in output voltage when under load compared to the Netgear SMPS, says to me its a much better unit.
The only downside is I've had a broken ethernet RJ45 plug connector clip & for some reason I lost all my NAS settings so could not get on with listening while I f-f-fiddled around sorting that mess.
Anyone got suggestions for ethernet port plug clips that don't break.
Posted on: 13 January 2016 by nigelb
Mike - thanks for the feedback. It seems that some of the improvements brought about by the iPower are not so subtle! Quite an achievement for such a modest bit of kit. Very clever if(i) they have managed to remove (cancel) a lot of noise with such a simple but smart design.
For a mere £40 it has got to be worth a punt.
Many thanks for your detailed testing and feedback - much appreciated.
I'll let you know how I get on when I get mine installed.
Sorry to hear about your ethernet plug connector woes - hope you got them sorted without too much angst.
Cheers
N
Posted on: 13 January 2016 by nigelb
Understood Mike and I also realise you have already done much to suppress noise in your LAN. I too have done quite a bit to optimise my LAN.
Even though subtle, it does however appear that there are improvements possible with the iPower and at £40 there is little risk. I'll give it a go and see. If I hear no difference then I haven't lost much.
Cheers
N
Posted on: 14 January 2016 by Mike-B
The only downside is I've had a broken ethernet RJ45 plug connector clip & for some reason I lost all my NAS settings so could not get on with listening while I f-f-fiddled around sorting that mess.
Anyone got suggestions for ethernet port plug clips that don't break.
Update - The broken RJ45 plug clip is contagious, another f-f-f-clip has broken. This is very annoying !!! Looking at the clips its pretty obvious they are not ideal for much other than a one click connection & will not take much in the way of in-outs & cable movement.
Anyhow, I've bitten another bullet & ordered two new MeiCord cables between NDX -switch - NAS. I am not a believer in ethernet cables other than engineering quality is far far more important the the price of snake oil & buffalo droppings. These cables claim to have a real quality plug & it looks like it. It also looks like the price of the cable is all about the plug & install labour rather than the cable itself; the price diff between 0.5m & 3m is £12.
So, here (or should that be "hear" ) - we go again, more later
Posted on: 14 January 2016 by RICHYH
Hi MikeB,
Before Christmas I, too, did the Ethernet switch power supply upgrade and my conclusions were the same as yours, a small but positive upgrade to SQ, more organic and open sound. I would recommend others to try this simple cheap upgrade for streaming.
Posted on: 14 January 2016 by nigelb
The only downside is I've had a broken ethernet RJ45 plug connector clip & for some reason I lost all my NAS settings so could not get on with listening while I f-f-fiddled around sorting that mess.
Anyone got suggestions for ethernet port plug clips that don't break.
Update - The broken RJ45 plug clip is contagious, another f-f-f-clip has broken. This is very annoying !!! Looking at the clips its pretty obvious they are not ideal for much other than a one click connection & will not take much in the way of in-outs & cable movement.
Anyhow, I've bitten another bullet & ordered two new MeiCord cables between NDX -switch - NAS. I am not a believer in ethernet cables other than engineering quality is far far more important the the price of snake oil & buffalo droppings. These cables claim to have a real quality plug & it looks like it. It also looks like the price of the cable is all about the plug & install labour rather than the cable itself; the price diff between 0.5m & 3m is £12.
So, here (or should that be "hear" ) - we go again, more later
Mike, I realise it is a bit late and you have ordered the MeiCord ethernet cables but you were asking about ethernet port plug clips that don't break. From your profile I am guessing that you have had this problem with the Supra ethernet cables. I use Audioquest ethernet cables throughout and have never had a problem with port clips breaking. Now I know you won't subscribe to snake oil but I have had great results from the better ethernet cables in the AudioQuest range. I use Vodka between NDS, switch and server (Unitiserve) and Cinnamon everywhere else. In fact I got sent the longer length of Vodka because the supplier was out of the Cinnamon I ordered. Not sure I would have gone to this expense if I had to pay the cost for Vodka. I notice you also use AQ Pearl ethernet cables. I wondered if you might be able to borrow some 'better' ethernet cables from your dealer to see if it is snake oil or if you detect a worthwhile improvement.
Have ordered a iFi iPower today and will let you know how I get on.
Posted on: 14 January 2016 by Mike-B
Hi again Nigel, a valiant effort on the ethernet cable sell, but apart from too late, no thanks I'm afraid.
Your very generous dealer supplying a Vodka instead of Cinnamon (or is that more indicative of the mark up I wonder) But that's just my sceptical dark side showing thru ........
I spent a few hours listening to cables, the most notable was when Cinnamon & Supra (plus others) were compared. The small group of us could not reliably differentiate between any cables on the Linn DS system, other than favour the one each bought to the session, that's one reason I bought Supra, plus its very high performance spec., which I've since realised is like using a Ferrari for a shopping trip.
The AQ Pearl I have was to complete the all Cat7 (screened) LAN between switch & wireless hub.
As it happens the broken clips came from both Supra & AQ.
I have the AQ hanging in the switch (just) & the switch to NDX section is now a temporary run around the floor with some Lindy Cat6 ..... £5 for 5m ..... !!!! & guess what ??? its as good, maybe, as the Supra. But listening to Radio Paradise is not a good test. But then again, the feeling of being better might be the new iFi.
Posted on: 15 January 2016 by Dave***t
Please forgive my thickness, but I find it a bit hard to unpick the conclusions from the above discussion. I've read in a number of places that SMPS 'wall warts' can inject noise back into the mains. I don't particularly understand what that means, other than that it seems likely to have a detrimental effect on SQ of other boxes. As a result, though I can't eliminate them, I try to keep SMPSs plugged into different sockets than my black boxes. If not at the other end of the room, then at least not on the same power strip.
Is that about right, at least as a description of the problem?
If so, is the upshot of this experiment that this iPower device reduces/eliminates that problem? I.e. does it mean that e.g. one of them could be used to power a network switch from the same 4-way as the amplifiers without SQ detriment? Or does the iPower do something else (obviate the need for shielded signal cables to some extent, for example), and other solutions are required for the noise injection problem - silencer devices, perhaps?
