I have recently change the switch mode psu our for a new quiet linear psu - this is a Chinese unit with input filtering - and very good well filtered regulation. The supply is 15v. I changed over the supply - and bingo sonically better stereo more detail excellent… however, the strangest thing is the treble output seems more detailed but lower in output - in relation to the original balance - not something I expected. It is early days yet - I will keep it in and see how it turns out. The NUC when running Roon with DSP is barely warm - with very little fan noise - the psu runs warm but not hot - it is rated at 15v @ 2.8amps. I have tried the NUC at full tilt gaming driving headphones,keyboard,mouse & HDMI … and the psu seems to cope - although it does get quite hot - as does the NUC.
Which DAC are you using? How is it connected to the NUC? USB, or via network / Pi / etc.?
Dac is in the naim nd555 and signal is sent via ethernet from nuc to nd555. It works well…
Do you mean that the NUC is not directly attached to DAC and the sound changes? It makes no sense for me.
My NUC 7i5 sounds better with an LPS as well. What it’s doing is feeding it cleaner power which lowers the electrical noise floor. That noise can be sent down ethernet (or USB). Esp when you have as sensitive a system as a top end Naim streamer, you’ll notice the differences. Ethernet switches as well. But I noticed with my microRendu and DAC V1. I would imagine a good properly rated LPS could extend the life of the NUC as well, but I’m out of my range on that one.
I noticed - that detail, voice inflection, stereo imaging and bass depth … all improved…not hugely but it is noticeable - a very nice upgrade. I have a Chris Jones CD rip …(can’t remember name of CD presently)… I was listening carefully to it and i realised…in the background of his recording - I could hear a cricket!!! I think my next target will be the WD Nas drive …
Are you sure that the noise is sent down ethernet? So, I guess you must also have a LPS for the switch itself and many others for the remaining devices connected to that switch.
I can admit that the device directly attached to the DAC via USB can induce electrical noise to the DAC, but no the networked devices.
Best regards.
Ethernet is galvanically isolated so how is this possible USB I can understand. Maybe the SMPS is passing it along the mains, I know Naim stuff is noted to being sensitive to mains noise.
So leave the old PSU plugged in ideally driving a load and allow it to continue polluting the mains. That Naim has extensive voltage regulation inside, so I very much doubt it is bothered by interference on the mains. If it is, I would ask for my money back.
I use a high end Cisco switch, which has a built in SMPS of good quality. The switch certainly bumped up the sound quality as well. I’m not sure if anybody knows what’s going on here, but I think the wisdom is, the changes may be subtle and of a small percentage, but make enough of them in the chain and they add up.
That high end Cisco increases the sound quality the same as any other switch that simple makes its job: to transmit data. That increase is 0%.
I always regret participating in these kinds of thread, but here goes 
I don’t think any of these observations have anything to do with the ‘bits’ being affected and I’ve rarely seen people claim the 0’s and 1’s are being affected, but it is always assumed by people that this what they are claim, for some reason.
It may be more to do with the signal integrity. I remember hearing these kinds of differences when I had a networked DAC (i.e. PSA DirectStream DAC with ethernet input).
There have been a couple of Cisco switches popular over on the Naim Audio forum for years. And there was a Naim engineer on the Naim forums that gave a really technical explanation of what may be happening but Naim now have a brand new forum, so I can’t dig up the old posts.
It’s always been long appreciated that ethernet’s little transformers provide great galvanic isolation but not perfect isolation. There is still some capacitive coupling…
Here is some idea of what may be going through those little transformers, possibly affecting SQ if it goes through the DAC and analogue cables/components…
https://audiophilestyle.com/forums/topic/37034-smps-and-grounding/?do=findComment&comment=735311
I’d love to see measurements showing this (they are coming apparently) but the technical mechanisms are plausible.
I’ve shown this to some very respected DAC designers and while they too are waiting for measurements , they don’t reject the technical mechanisms that John Swenson discusses…
I only participated because I find this stuff interesting (the potential technical mechanisms at play). This is certainly not life and death of course - just a fun hobby. I hope nobody gets too animated in the discussions 
I understand you, @dabassgoesboomboom, and I appreciate very much your opinions, of course. As you say, this is a fun hobby. I am not The Master of the Truth either, I have just written down my point on this matter.
Hi good response to my thread all I know is that I am hearing more detail and sense of space I stereo…I do use dsp in Roon so this may get effected by mains artefacts…
Yep. And it didn’t cost an arm and a leg like the audiophile ones do. Well, it would new, but plenty of bargains on the used market. It’s to do wtih clocking, the PHY layer and many other things. If an ethernet cable can change/tweak the sound, then it seems obvious that a big piece of hardware like a switch will have an effect too. Greatbthing is I have two diffrent systems running through the switch as well as whole house traffic, and both systems sounded equally better after adding it to the network. Way better than a JS shunted Netgear or other consumer switch, even with their own linear power supply.
Yup that was the gist I remember reading the Naim (or was it Cisco?) engineer write about - all things that potentially improve the signal integrity (SI)…
The cables too? Clocking? Signal integrity? Really?
Definitely this topic is not for me 
My ears/system gain, yours loss. Each to their own. Best.
From my experience … the whole chain is pretty sensitive…I think mains noise induces jitter and low level anomalies…but I am no scientist certainly my new linear psu on my nuc has made a significant and very worthwhile improvement…delighted.