DoP on the Digital Input to an NDS

My understanding was that the S/PDIF input of the NDS would accept DoP format upto DSD64.

When I present a DoP stream, the Naim app records as having a Digital Lock on the input, but nothing is processed.

Converting to PCM with the DSD64 coming in as 24/192 and the processing works in the Digital input. Still shows as Locked.
Transferring the DSD64 stream to the UPnP input and the DoP is handled and the DSD64 played (recorded as DSD64 in the Naim App).

Is this a bug in the latest version of the Firmware or just a limitation of the S/PDIF input?

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Oh, I have the Specs

I have these announcements

Which sort of suggest DSD64 support over the S/PDIF digital inout

I’m assuming you have the latest firmware?

I do - 4.8.0 (14776)

As I was testing the HLS streams in the Beta release prior to this going to 4.8.0

I don’t have an NDS but do have an nDAC which works fine with DoP
Are you using Roon?

I am using Roon to feed the NDS on its Digital input, through an UltraRendu with a XMOS based USB->S/PDIF convertor

The Roon Ready Diagnostic indicates that the convertor is good for the Encapsulated DSD64 (2822400/1/1 & 2822400/1/2) and Encapsulated DSD128 (5644800/1/1 & 5644800/1/2) formats

This is then limited to DSD64 in the Device Setup

Then during Playback

This is the playback processing in Roon

And this is the DAC Diagnostics

Stream 2
rate: 176400 (176400/1)

Which is DSD64 encoded in PCM

And the Digital Input status is ‘Digital signal locked’

So why isn’t the SPARC not processing the DSD encoded in the PCM stream coming in on the S/PDIF input?

I can even get to upconvert the DSD64 to DSD128 through the DSP in Roon

And this reported correctly in the DAC Diagnostics in the UltraRendu

But now the Digital Input status in the Naim App is ‘Not connected’

Sorry, can’t help. Maybe @Stevesky can assist here.

Good morning,

DSD is supported in 2 ways on the older streamers like the NDS:

  1. The streaming module deserialises the bitstream out of a DFF and DFS container stream and then packetises it over to the DSP that then does a direct dsd conversion to the DAC IC.

  2. The DSP handles the SPDIF in, detects the DOP signatures and based on that depacketises the bit stream and again does a direct dsd conversion.

In this case we are talking 2) - this thread is mixing up 1) into the mix.
We haven’t updated the DSP code for about 6 years now and having done a quick spot check (old Oppo dvd player to naim streamer) it works fine. The Naim implementation is based in the old DCS spec who drove the DOP standard a long time ago.

A few suggestions:

  • ensure a coaxial cable is used, not optical. The optical rx doesn’t have the bandwidth to handle it.
  • get the system playing 176.4kHz/24bit PCM natively first. That is the baseline and then proves all physical links are working,
  • see if there are any firmware updates for the usb to spdif adapter. I’ve got a feeling it is not doing the dop conversion properly. If it was getting it slightly wrong then very distorted ‘noise’ will play in the NDS - in your case its silence indicating its sending out zero value samples.

On a side note, dsd128 will never play as spdif does not have the bandwidth to carry that much data. Only dsd64.

Best regards

Steve Harris
Software Director
Naim Audio Ltd.

1 Like

Hi Steve,

Thank you for your response.

Yes, coaxial is being used. The TOSLINK input on my NDS is unused.
Yes, DSD → 24/176.4 PCM does play through the Roon → UltraRendu → USB to S/PDIF convertor → NDS Digital In

There are 4 settings for DSD in the UltraRendu

  1. None - this prompts Roon to convert DSD source (diff/dsf files) to PCM - the DAC Diagnostics report this in Altset 1 as 24 bit at 176400 (176400/1) - the Naim NDS has a digital lock, decodes and plays the source

  2. DoP - this should encode the DSD into a PCM stream - here the RoonReady diagnostics reports DSD as supported as Encapsulated - the Device setup in Roon shows and max DSD is set for DSD64 - the DAC Diagnostics report this in Altset 1 as 24 bit at 176400 (176400/1) - the Naim NDS has a digital lock, but there is no sound

  3. Native DSD - this shows in the DAC Diagnostics as Altset 2 SPECIAL DSD, however Native DSD is not supported over S/PDIF and the NDS has no Digital Lock

  4. dCS - I had not tried this mode before, but is a DoP mode - the RoonReady diagnostics reports DSD as supported as Encapsulated - the Device setup in Roon shows and max DSD is set for DSD64 - the DAC Diagnostics report this in Altset 1 as 24 bit at 176400 (176400/1) - the Naim NDS has a digital lock, but there is no sound.

So I would go back to Sonore on the dCS mode, based on your response, but I am also thinking that the XMOS U8 based USB → S/PDIF is not passing the DoP stream correctly, as the weakest link in this chain.

@Stevesky One further thought - it has been long been talked about the available firmware space limiting new functionality for the BridgeCo. based streamers.

If you were to remove the Tidal and Spotify integrations and iRadio would there be room for a RAAT-based RoonReady integration?

My thinking is that if you are using Roon, you are using that Tidal and Internet Radio station functionality in Roon and just need the Streamer to be a RoonReady endpoint nothing more. Did anyone ever use the Spotify integration?

I know it would involve having 2 supported versions of the Firmware - one just for RoonReady and the current one - but the current one is not changing anyway!


Hi @Stevesky

Just been going through an old Oppo manual…no mention of DoP or the old DCS format? Infact digital audio out when playing a SACD is not supported over COAX just HDMI.
And even if this is possible on a model, it is likely to be just converted PCM 24/176.4 and not DoP…ish_manual.pdf

How do you know on the NDS that DSD content is being processed?

On the Ethernet input, when DoP based DSD64 is being streamed in, the status “Now Playing” indicates DSD64 content.


Is there any update here?

Hi @simon.pepper

I had to dig back on the Oppo as its a very old device. To enable DOP DSD on it there is an undocumented startup key sequence press. Similar affair to change region code… :slight_smile: The reason for this is that licencing wise DSD bitstream is not allowed out on a digital interface on a SACD disc player and can only be decoded internally.

In the case of the NDS the DSP feeds back to the host micro what it is doing which eventually gets shown on the front screen and app.

DSD DOP on SPDIF is quite a niche thing as there has always been licencing and legality issues on streaming it if the device plays licenced media like SACD’s. If the device is a generic DSD file format player (like the NDS) then there are no restrictions, but of course someone has had to get the recording into DSD file format in the first place. In practice most of it is from where people have ripped SACD discs using hacked playstations or similar hardware.

Best regards

Steve Harris
Software Director
Naim Audio Ltd.

Yes, I am aware on the Licensing for a physical SACD player, but subsequently there are a few places providing downloads in DSD format

E.g. and HDtracks

Or recording in DSD such as and releasing those recordings here Blue Coast Records Titles | Blue Coast Music

So I have quite a number of albums in dsf format.
As stated I can play these on the NDS via the Ethernet input either by Asset UPnP server (ensuring the setting for this format is ‘as is’ where it is sent as DoP) or via the SonoreUPnP Bridge where the DSD is packaged as PCM WAV files, and unpacked by the NDS DSP.

So why can’t this be undertaken on the S/PDIF based digital input?
The XMOS based USB → S/PDIF convertor is ‘seeing’ the digital stream coming from the Roon Core and outputting as DoP on the S/PDIF output (though I have no way of confirming this, as no other DSD processing DAC available).

I am looking to validate that using the Ethernet input on the NDS is better than the S/PDIF based Digital input for all format types.


Hi Simon,

I can’t talk for the XMOS solution, but in the case of the NDS it is DOP compliant on the SPDIF input. As mentioned I’ve tried this feeding it with an Oppo Bluray and a Naim streamer (NDX) as a source. They both play.

For reference, the NDS implements this spec:

Typically if DOP is not getting detected its because the source device is not correctly encoding it to spec, or the link from PC → USB is not bit perfect and that in turn messes up the DOP encoding.

I would suggest pick this one up on the Roon forum, as I have a feeling this is a Roon side issue. eg, they may be just sending raw DSD to the soundcard not knowing if the soundcard has a DAC in it, or an SPDIF out and hence need to do the DOP encoding.



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