Advice please. Bought several separates on a well known auction site almost 2 years ago, the list is
NDx2 streamer, 555ps DR power supply, Nac 252,pre amp supercap DR (this was new) NAP 300DR, PMC Twenty five 22i speakers on their dedicated stands Chord Epic cables and interconnects. All was fine until about a month ago when the sound quality has headed south, l can only describe it as ‘edgy’ and it makes me wince listening to it, my question is one or more of these components needs a service but lm unsure which one, any ideas?
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And it could not be where you are in life, say exhausted, tired, stressed etc. It’s easy to think the system is always the issue but all this and more can heavily effect the perception of audio quality 
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Hard to tell without knowing ages of kit. Have you introduced any other electrical items in the house around the time you noticed the drop in SQ ?
I’d suggest a first step might be to power down everything, strip it down and rebuild the rack(s), giving you a chance to plug and unplug cables, cleaning the plugs and sockets in the process.
If it’s still sounding off after that then it could be time to look at getting the older pieces of kit serviced if old enough to need a service. You can look up the serial numbers to see when each item was made.
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The 300DR may well need a service. It’s a regulated amp so should be serviced every about every 10 years.
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Do regulated amps need more frequent service than non regulated?
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Yes. Definitely.
You should work out the service history of every Naim unit you have, starting from when they were made.
After sorting the NAP300, then look at the Supercap. IMO…
YMMV… 
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I am not sure regulated products need replacing any more often than unregulated ones… so no they don’t. Most if not all electronic devices use components that age through chemistry and heating, and over the time this process moves the components outside of tolerance (and in extreme cases to failure), and once outside of tolerance the performance of the electronic component can be impacted. Electrolytic capacitors used in low frequency decoupling and smoothing are renown for aging and needing replacing. As a component they are specified for a number of hours of use for example. After a while they need replacing… often around 10 to 12 years.
It is unlikely they will stop working after 12 years and go to 40 to 50 years or longer, but they will perform quite differently at that point,massuming they haven’t failed.
It can be worth when a system of severeal components goes off, taking apart and disconnecting, then rebuilding, perhaps cleaning connections in the process. Naim Burndy cables benefit from flexing to loosen the cables that can settle over time… sound silly but can be beneficial.
However edgey and wincing has me thinking of other things… specifically room reflections or acoustics. Has there been any new decorations, furniture or moving things around… this can make a really really big difference in your listening position, especially when you become used to a certain ‘sound’.
BTW I think some confuse powersupply reservoir decoupling that exist in nearly all rectified powersupplies, with regulated powersupplies… these are quite different. Both regulated and non regulated powersupplies use reservoir electrolytic capacitors, and strictly speaking non regulated powersupplies are more sensitive to electrolytic capacitor aging than regulated. Any rectified powersupply whether regulated or non regulated will suffer from electrolytic capacitor aging… but Naim state the sonic effects in their regulated designs become more noticeable as their components age.
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On the regulated vs non regulated issue, perhaps the components last the same time, but the impact to a regulated design might be more drastic one a service becomes due? There are a few posts about this, here’s the first I found
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First, before considering anything else, assuming nothing has changed in your listening environment, power everything down. Unplug and re plug all cables to clean the contacts then have another listen.
If no improvement, list all the serial numbers and determine the age of each component using Naims serial number list. Assume any of power amps or supplies over 10-15 years old may need a service. You can check whether they have ever been serviced at Naim with Naim support and whether the service period can be pushed to 15 years. Then get what needs it serviced. Then have another listen.
Take it from there. 
Just noticed this advice has been given above. Take this as a Plus 1. 
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@gthack - I think you have it. The problem is that the regulated NAP can go rather… odd, as it ages. Whereas a non-regulated NAP fails far more gently…?
[regulated NAP’s - 250 and above; non regulated NAP’s - anything below a 250.]
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That’s very kind, I appreciate the response, but I’m really just quoting others, Richard in this instance Please don’t take my contribution here as representing any sort of earned knowledge, other than spending way too much time on this forum when I should be doing more productive things 
Hope the OP manages to track the issue down! @Thefox any progress on working out the ages of your kit?
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As I mentioned above it is highly likely a regulated amp masks the reservoir caps in the rectification smoothing stage to some extent to the point it impacts the regulator too much and so fails more noticeably over a short space of time - where as the unregulated power supply will gradually decline over time and so will be less suddenly noticeable.
However both are declining at the same rate - its just the regulated one is more initially masked by the rectification reservoir capacitors down stream regulator, and so impact on SQ performance varies.
A graph of a typical ESR deterioration over time for an Electrolytic capacitor- these do vary for capacitors - and it is almost certain Naim use devices with a greater life expectancy. The higher the ESR the less effective the electrlytic/reservoir capacitor is at smoothing and with a regulator the harder it needs to work.
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@gthack @Simon-in-Suffolk - I think we are really all on the same page, with this… 
As a 250 owner (*), since 1985… The longest mine went was 18 years - to its 1st service (at Naim). Subsequently I have had it serviced every 10 years (at Class A).
Conversely, my spare NAP, a 140, I had serviced at +28 years - and it was still sounding OK.
YMMV, as always… 
(* - If I had a classic car… which I do not… I think I would change the oil & filters regularly.)
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have you introduced a new element to the electrical circuit which could cause the sound of the
hifi. Naim’s are very sensitive to that
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