Here’s my dilemma: I’m interested in adding a power supply to my nDac (fed by an Allo DigiOne Signature into a Supernait 3). It seems I have the opportunity to buy either an XPS (serviced in 2018 and upgraded to DR IN 2019) or a CD555 (not serviced, non DR) for about 1000 USD more.
What’s the better option? Does the CD555 need a service to be worth it? Based on the serial number it seems to be from 2008-2009. Are there other options I should consider?
I have a XPS DR with my nDAC and it’s wonderful IMHO. Servicing isn’t cheap and it’s more expensive the higher up you go. I would think 2008-2009 would be in need of servicing asap, so factor that into the costs. (at least $2600 IIRC)
Forum lore would suggest that the non-dr 555 works best with the nDac but I think it’ll be harder to sell down the line as they’ve stopped doing Dr updates. If I had a ND555 I’d want a 555Dr to run with it.
When I was running an Ndac a while back I used both an early 555 and then later a 555DR. Both work really well. Some say the stock non-DR supply works slightly better. I can understand why as it seems have a slightly lighter more playful tone than the darker but more real DR version but to be honest the difference isn’t worth losing sleep over!
All 500 stuff has a 15 year service interval, so the 555 you’re interested in should still be okay. In the UK I reckon you’d pay around £2-£2.5k for a 555ps of this vintage with no service history. I think a Naim service is now around £800, which kind of makes the math work as I expect £3k is what you’d pay for a serviced non-DR version.
Make no mistake though, a 555ps on the Ndac will make it a formidable piece of equipment unlikely to be rivalled by anything close to this price. If you want to see what digital is capable of then a 555 is the way to go.
A CD555 is a CD player, surely…? Did you mean a 555PS… perhaps…?
The 555PS is labelled CD555PS which is a bit confusing
Edited to add:
Before anyone else tells me why the CD bit is there - I already know 
Not exactly what you asked for, but let me share some of my past experience and some advice:
I used to have a similar system: Allo Digione Signature/Allo Shanti PS → nDAC → SN2/HiCap DR → Dynaudio Confidence C1.
Some time ago, when auditioning potential upgrades, I demoed a 555PS DR into the nDAC. I heard zero difference. I assume this was down to:
More recently, while auditioning a pair of Audiovector R1 Signature (which was a better match with the SN2 and thus much better resolving that the Dynaudios), I compared ND5XS2 vs Allo Digione into the bare nDAC. The difference was very significant, with more weight and authority in the sound and more goosebumps as a result!
I have now ended up with PMC twenty5.21i and a ND5XS2 for your reference.
My advice: It would be a better use of budget to improve the streaming source rather than the power supply. nDAC is well known to be sensitive to the quality of the signal it is being fed with. That said, I wouldn’t be able to resist getting a 555PS if I found one at a good price (and I had some spare money to spend ). I would probably skip the XPS as I would end up to a 555PS down the road anyway! 
555 CD PS was light years ahead on my CDS3 compared to XPS. The ultimate Naim power supply even non- DR imo.
Yes, sorry. It’s a CD555PS.
It was explained on a factory tour that to remedy this situation, i.e. instigate a name change Naim would have to jump through re-certification hoops, globally.
You can understand why Naim decided to keep the name the same!
get the serviced xps and you’re done.
Forseeable upgrades being
speakers, then
amp and
digital companion if necessary.
IMO @sihctr suggestion of considering a streaming source upgrade makes a lot of sense. I suspect you’d get a notable uplift in SQ.
That’s an interesting idea. I hadn’t thought of using an ND5XS2 as a streamer only. I was basically hoping the nDac would take 0’s and 1’s fed to it via the Allo and do its magic. I’m also using the Shanti Power Supply into both the RP3 and clean sections of the Digione, so my hope was that noise would be minimal. I guess all I can do is try to find a way to compare both devices in my system.
When I was using an nDac I found that the 555PS was miles better than an XPS2. In my view the XPS offered little more than the XP5XS I was using at the time. The 555PS (initially non-DR) gave an uplift in performance that was huge.
As others have said the nDAC is sensitive to the quality of the digital feed. Also the 555 power supply is going to need a service very soon. A better source, such as ND5XS2 and serviced 555PS on the nDAC should be an outstanding front end. But, if that’s too pricey, I guess it’s ND5XS2 and XPSDR vs Allo DigiOne and 555 and which of those would sound best only you can really decide. Is it possible for you to listen to both and do a comparison?
Roger
Originally designed to power the CD555 hence the CD prefix
I was hoping (and expecting) the same thing; that Allo should be more than enough. My dealer was adamant that this was not the case and brought a ND5XS2 at my home to compare. I was not expecting to hear any difference, so I was biased against it, but the differences were obvious, repeatable and significant… unfortunately for my wallet!
Do try to audition one as a transport into the nDAC (or alternative streamers as well; there are some relevant topics ongoing in the forum). I didn’t want to mix different components visually, so ND5XS2 became an obvious upgrade for me.
I agree 
In 2011 I used an ndac with the digital out of a rotel cd player. Adding an XPS didn’t really improve sound quality.
I now use an ndac with primare NP5, streaming transport/Ifi power supply.
Sounds very good. No real urge to add a power supply.
Indeed, and interestingly I found the 555PSDR matched less well with my NDAC to my ears compared to the nonDR 555PS.
I did a side by side comparison at the time… it was also interesting that I found the NDS seemed to sound better with the 555PSDR, and not so happy with the 555PS nonDR… but I preferred the nDAC 555PS nonDR overall.
Funny how everyone’s experience/system(room, gear, ears) is different. When I added a XPS-Dr to my nd5xs2/nDac combo I noticed increased SQ for everything. For the first week however I did have a little buyers remorse (nd5xs2/nDac alone is very very good)but once it was run-in I could fully appreciate what it was doing. Clearly the 555PS gets all the love but the XPS-Dr is no slouch either and it’s much easier to find/acquire in North America.
My point was, the rotel wasn’t a good enough source for the ndac. So adding a power supply didn’t make much difference.
You’re using a good source, so the power supply does make a difference.
IMO, better to ensure you have a good enough source before adding a power supply to the ndac.