I’d suggest that your friend is in a minority. I swapped from XPSDR to 555PSDR on my 272, which has only one Burndy connection, and the improvement was very, very significant, and far greater than that gained from adding the XPSDR to the bare player. I’m not made of money and would not have made the switch were the improvement not worthwhile.
There is much more to the 555 than the two outputs. You’ll get a similarly large improvement on the CDS3, NDX, nDac and various other boxes with a single Burndy connection.
The difference between an XPS2 and the 555 is noticeable in almost all cases but the caveat is “almost all”. I stuck with the XPS2 on my CDX2 because the 555 exposed the weaknesses of the CDX2. Better is not always satisfactorily better. On the other hand pair it with a CDS3 and that is close to being a completely different machine in a wholly positive way. The difference is profound. Ditto the 272.
On the other hand I’ve also heard both on an NDX2 now in 3 very different situations and I’m very clear that the 555 did nothing obvious that the XPS2 didn’t do. I offer no technical explanation as I don’t have one but I’m very clear in what I heard. Offered the choice I can see no justification for adding a 555 to the NDX2.
Mike, that’s interesting. My point was that TGR was suggesting that there was no difference between the two supplies on any box that had as only one connection. I don’t agree with that, and clearly neither to you.
Obviously a SN3 maybe the limiting factor here. However with NDX 2 on a NAC 252 & NAP300 DR things change, quite a bit presumably. My experience was in a 500 Series setup at the Bristol Show. It wasn’t subtle.
I feel that on 272 it’s not the same, because 555 dr will power both the pre and dac.
On Nds and Nd555, it will power both the digital and analog stages.
However on Ndx2, the 555 dr will not be fully exploited.
But I don’t say that 555 dr won’t be better vs Xps dr on Ndx2, but not in the same proportions as for the 272, Nds and Nd555.
But I am speculating, as I haven’t done the test on the Ndx2.
Stephen, you are correct. The smoothing caps in the 555 are significantly bigger than those in the XPS. They are the typical large caps that Naim use in a lot of their PSU’s. Where as the ones in the XPS are very modest by comparison. I’d expect the XPS ones are about 5000uF? compared to 3 times that for the 555. And yes, the transformer is stated as being 40% bigger. Both (now) have the discrete regulators. Looks like 6 for the XPS and 7 for the 555 ?
So, without the DR bit, you’d expect the 555 to provide a more stable output voltage. With DR, the differences should be much less.
I’m still interested to hear from those that can or can not hear any differences. It sounds like the better PSU suits a better source. Yes, you can fit the 555 in place of an XPS on a lesser source, but you may or may not hear the differences.
Me, no options to play on my CD5si or ND5XS2
I think that Thegreatroberto’s friend has made the right choice as if i understand correctly she went with the XPS DR over 555 DR on a NDX 2/SN3 based system. This makes perfect sense in that context of her system and her demo. It’s the natural partner for a NDX 2 and is also a great saving if it were to go the other way and rinsed even more money, should one would want to go even further on the upgrade path!
And that sort of answers the original question. Given that the PSU is ( in this case) for an NDX2, is there any advantage for going for the 555 over the xpsdr?
Maybe a better source may see ( or hear) a benefit of the 555. And certainly any source that can use both of the cd555,psu’s sockets should be paired with the 555.
For me the answer lies inside the two units. Yes there are some extras in the 555, but unless your source can use them, you may not hear a difference. The real clever bit is within the Dr regulation. This clever bit is the same tech in the xpsdr as the 555. Just that the 555 has a larger TX and huge caps. Which will make the dr’s life easier.
Once you throw the pound notes into the equation, the answer becomes clearer.
My friend paid £2500 for an ex demo xpsdr. She was not offered an ex demo 555, so would have had to pay for a new one- subject to any discount she could have leveraged. And at least a six week wait.
Using your logic the 272 must be miles better than the NDX2, as the 555 is hugely better than the XPS when used to power it. I’d forget theory and use your own ears.
