555 and 555DR on NDS
Posted by: yorkslad on 06 February 2015
Very first post here
I have an NDS that i was using with an xp5xs power supply originally
I then loaned a friends non DR 555 power supply and this did elevate the level for sure
On this basis i sourced (and bought used) a 555DR and did a comparison that has left me a little unsure
With the non DR 555 the music flowed a little more but had much less control
With the 555DR there is a lot more control but the music flows a lot less (sounds more digital)
I then tried them both on the NDS while swapping options of digit / analogue feed to each
Final summary is that the 555DR on the analogue side (outer connection) and non DR on the digital side (inner connection) gave the best result so far
I am now wondering if getting another 555DR would be the way to go or would another non DR 555 be the better option
It has to be pointed out that the non DR 555 had been up and running for 3 weeks while the 555DR had only been up and running for 3 days (even though it was used before this time)
Ideas and observations from experienced users appreciated
Although naim doesn't officially state it, there are reports of further improvements to be had, beyond a dual 555PS setup, by just stacking a few additional 555PS in the vicinity of the NDS. The NDS seems to benefit plainly from the proximity of these weighty power supplies (DR or not is secondary here). Effects are audible, particularly at low frequencies, even when the additional 555PS are not connected to the mains - with the nice side effect of this being energy-neutral!
Cheers,
S,
Stefan - are you saying that having the extra mass from a couple of un-connected 555PS supplies on the same rack is making a difference (so the same could be achieved with a load of bricks, lead weights etc...)
James
Silly me...I thought Stefan was joking!
I place heavy books on empty Fraim shelves just as a precaution. But I would question any other "proximity effect" from idle PSs. We do know that large torroidal supplies send EMI up and down (from the right hand side of the PS enclosre), so perhaps placing idle 555PS's above or below could suppress some of this radiation?
But talk about an expensive way of adding a bit of shielding!!! 
...
DR555 on input 2 and non DR on input 1 seems the best configuration i found when mixing 555 (more settled than previous with better control and transparency)
...
Interesting findings Yorkslad, and thanks for posting!
If I look at the manual, it see that Burndy input 1 is for digital, and input 2 is for analog.
You prefer the DR'ed supply on the analog input, whereas Chris Bell prefers it on the digital input.
Harry liked what he heard with the DR'ed supply on the analog input, but wound up with DR'ed supplies on both.
Sounds to me like two 555PS's are a winning NDS upgrade in any combination. Very tempting! 
Someday perhaps...
Hook
Silly me...I thought Stefan was joking!
I did too!
If you've got the money have a listen. Can't hurt. But prepare not to have the money thereafter.
I have a friend in Seattle with a nearly identical system and he prefers the DR into the analog side and non-DR into the digital side. The arrangement of the power supplies appears to be somewhat subjective... I'm sure 2 DRs are magical.... my DR Supercap transformed the Superline it powers.
Were you using the 552's AUX2 before getting the SC?
This is the other PS upgrade that's been tugging at my heartstrings. Dr. Steve and others have said here that it's a big step forward, but I also recall Chris Koster telling a couple of years ago that he was staying with his 552's AUX2.
@Harry - that's exactly why I've hesitated...I'm a sucker for audible upgrades!
Yikes, this is turning into a scary thread for me... 
I've got that block too Dusty. We're not by any chance using the same system in parallel universes? Stranger things have happened.
Sorry Harry, I completely missed this...and yes we are and were and always will be 
X 2 555DR for me. Yes, I contemplated real hard for a long time re Hugo and stayed true to Naim....as always! Yes more expensive, but I know that with Naim!!!!