So, to clarify. A Core connected to the Ethernet input on a ND555 has the signal routed through this NP800 board then to the DAC, but if the Core is connected to the BNC input, the signal bypasses the NP800 board and goes direct to the DAC. Is that correct? In which case, using the BNC input would avoid sound changes associated with the firmware?
I get your point here. 3.8.8 lacked the defintion of 3.10.1 but a small but negative element of 3.10 still remains and your glass analogy is a fair one. I hope that 3.10.2 will combat this whilst retaining all the positive things. Plenty to like about the latest FW!!
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No you are not quite correct.
The NP800 network protocol module is only used for Ethernet, WLAN and USB applications as you say, but itās separate from the main digital streaming engineā¦ it is separated by LVDS to help with electrical noise isolation, and is treated like one of the digital inputs into the streamerā¦ essentially itās a custom designed protocol bridge.
The core part of the streamer engine, the digital streamer board processes and controls the different digital signal feeds into the Streamer, whether they be from the NP800, SPDIF coax, Toslink, Bluetooth etc.
It is this digital streamer board that is controlled by the ARM CPU. It is this CPU that is ātunedā, if required, in software updates. This board undertakes the master clock management, as well as the digital audio signal processingā¦ and conditions the signal for analogue conversion, or digital output by converting to SPDIF.
Therefore this software controls all streamer inputs, such as SPDIF, the NP800 network inputs etcā¦ and any consequently software tuning affects the entire streamer operation and all inputs.
This also means software updates can equally affect digital audio and analogue audio outputs, and indeed I can attest to this.
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Exactly, the Nd555 is used only as a dac. But you canāt have Qobuz neither Tidal. The Core streams his local files.
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So, this means that any input going directly to the DAC via SPDIF will still be affected by the tuning Naim do the ND555. Listening to rips from my Core or streaming music via my Node can all be influenced or coloured by the firmware/tuning?
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Nothing goes directly to DAC as Simon has said.
All goes through digital board/DSP before DAC.
And hence all sources influenced by FW changes.
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Have you checked thereās not a fat man in a red suit and a bunch of reindeer out there, interfering with your leccy supply?
Merry Christmas Richard and all forum members.
Roger
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Hmm, rather blows the theory of those using different digital transport as a firmware work around then. Though all those double ended arrows makes the signal path somewhat confusing. Not entirely clear that the digital inputs go to the ARM?
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Interesting, so that means that you canāt effectively ever use the ND as a true stand alone DAC without the influence of the firmware/tuning. I didnāt realise that. Iām starting to see the benefit, a few have mentioned on here, of separating streaming and the the DAC components.
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Thank you @Simon-in-Suffolk for your infinite patience with the layman.
With the aid of your explaination and the block diagram posted on the āHappyā thread, I believe I now have a rudimentary understanding of the signal paths and processing of sound shaping within the ND555 architecture. Thank you!
As suggested by @Richard.Dane I will continue to monitor the sound signature of my system until the New Year, hoping it settles on a sweet spot.
It is still not clear to me if uniform FW is implemented across the Naim Streamer range?
As would be expected, Owners of the flagship 555 Streamers appear to be disproportionately affected by the changes in sound signature caused by the recent FW updates. Whilst I am very happy that folk are happy. If the sound signature is not spot on at the top it certainly wonāt be at the bottom. It is just not as visible.
Given the Ā£35k+ Owners have invested in this front end it is not unreasonable for Naim HQ to take note of our feedback.
Personally, I would be happy to return to the sound signature my system had prior to FW3.10. However I also concede that there has been some improvements in resolution and the presentation of percussion. Unfortunately these changes are not IMO currently in balance with the over presentation, as eloquently described by geko and drago.
Have a wonderful holiday and I will hopefully see you all back here in the New Year with some good news to report.
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The DSP is not linked always with the dac ?
Maybe the main difference between each firmware is how the dsp interacts with the streaming board ?
yes
In Naim designs yes the SHARC DSP is always linked with the DAC and digital audio output, the SHARC does many functions, itā s an advanced device controlled the by the ARM CPU controller and the master clock and in many ways is the heart of the streamer. When the streamer is analogue audio mode the DSP chip (SHARC) also undertakes the oversampling and low pass reconstruction filtering function, as Naim disable the oversampling and filtering functions embedded in the DAC chips, such as the PCM1704K -as I assume they prefer their own implementation performance and is more flexible. When the streamer is in digital audio mode, the SHARC creates the new and sometimes modified SPDIF signals to be send to the Digital output.
The oversampling and low pass filtering using an IIR based filter has been unchanged since the days of the NDAC, though faster and better SHARC processors have been introduced through the years.
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Thanks a lot - I learned that the phrase ānever took a runningā¦ā is more wide as I thought and I also learned that a 500 System can be joy and pain 
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Thereās life in the old nDac yet!
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Or in an nds used as DAC only ā¦ maybe even a bit better.
Except you canāt insulate the combined streamer/dac devices from the effects of firmware upgrades, as @Simon-in-Suffolk states. Or is it that the NDS is no longer updated? 
AFAIK there is no further updates coming - and if so, you can rollback by yourself
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I knew I shouldnāt have sold it!
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I have not done so 
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