Singxer SDA-6

[SwissBear]

Hi everyone,

 

I wanted to open this thread to invite people who have an interest in the SDA-6 DAC from Singxer to share their experience and their thoughts.

 

I first became interested in this DAC after noticing that it was offering a 10 MHz clock input. Why so ? Because, for a very long time, I have been a big fan of external clocks and an early adopter of the famous Mutec REF-10. I always enjoyed the naturalness these clocks were offering to music reproduction. But, for a long time too, having a DAC with a 10 MHz clock input was reserved to the elite of DACs, like CH-Precision here in Switzerland, or dCS. And as enthusiast as I was about this technology, I always remained on the sidelines when using it, limiting myself for budget reasons to producing a clean SPDIF flow with a Mutec MC-3+ USB driven by my REF-10.

 

I then decided to follow the HQPlayer track and upsample my music outside the DAC, using this wonderful piece of software. And this led me to change my DAC and also try using a Singxer SU-2 as an USB → I2S interface, to produce a clean I2S flow, correctly clocked by my REF-10.

 

This led to very good results with a Singxer SU-2 + Matrix Audio x-Sabre combination, as this DAC offers the possibility to not use the clock of the DAC and rely on the clock signal of the I2S flow. This produced less impressive results with a Topping D90, despite the helpful support of their technical team, as this DAC does not offer the possibility to disconnect the jitter correction process (PLL) of the DAC. But I had a good idea of what those DACs would sound, and I loved the music presentation of the AK4499 which is the heart of the D90.

 

After reading @barrows explanations about the NOS mode of the AK4499 (https://audiophilestyle.com/forums/topic/60497-ak4499-dacs/?do=findComment&comment=1088538),

I decided to dig a little deeper into de specs of available AK4499 based DACs, only to discover that the SDA-6 of Singxer was offering the complete set of requirements I had:
- a close to perfect galvanic isolation of its USB input, which is already available on its interfaces like de SU-2
- a mastering of the integration of external clocks, which is also demonstrated by the SU-2
- the use of the NOS mode of the AK4499 when playing DSD files
- a nicely designed fully discrete output stage

 

I then looked at the tests made by l7audiolab in China (https://translate.google.com/translate?sl=auto&tl=en&u=https://www.l7audiolab.com/f/measurementreview-of-singxer-sda-6/), which were very convincing of the nice implementation of this AK4499 chip made by Singxer. And I contacted them to have a better understanding of the benefits of using an external clock with their DAC. Leter from Singxer kindly provided these measurements and allowed for their public usage.

 

 

 

Setting the DAC was straightforward. I used a 50 Ohm connection on my Mutec REF-10 (though the SDA-6 also supports 75 Ohm clock connections if suitable). And just started playing DSD256 files produced by HQPlayer. 

 

And I am in the place where I have been dreaming to be for a while now. The sound produced, even without the unit being broken in, is awesome. Full of details and nuances at the same time. The SU-2 + x-Sabre combination was very good, bot sometimes a little bit bright for my taste. 

 

This SDA-6 DAC is as resolutive as you could imagine, but with a kind of nuanced manner. If you have been making photography, it’s kind of like moving from a very good and sharp Nikon or Canon lens to an equally sharp but more nuanced Leica Apo-Summicron… A balance of detail and subtlety in the rendering of music that I really appreciate.

 

Hope this helps and looking forward to reading your own impressions.

[SwissBear]

5 hours ago, w1000i said:

What a good start. Did you ordered the advanced version or standard ?

 

My self got Singxer SA-1 Headphones amplifer which on paper the cleanest amp ever made but the important is how it sound and it is really shocking 🤯 epic with Focal clear pro.

This company has some good engineers and I start to trust it. Next step maybe SDA-6 Advanced.

Hi,

 

I ordered the advanced version. And I think the upgrade is worth it. 

BTW, the SA-1 is a nice complement to this SDA-6, which output voltage in DSD is a little tiny. Using the SA-1 as a small pre-amp could be a nice opportunity for you.

[SwissBear]

4 hours ago, matthias said:

 

Very interesting, thanks for sharing.

 

Please, can you shed some light on the sound signature?

Is it more forward sounding or more laid back?

What about dynamics, slam and PRaT?

 

Thanks again

 

Matt

 

Hi Matt,

 

I described the sound signature of the x-Sabre with the ESS chip as a little bright for me. Kind of shiny and glossy.

On the opposite, the D90 was a little matt. 

The SDA-6 is just transparent, at least in the mode I use since I received it, which is NOS.

It's very relaxed and non aggressive. You can, as I do, listen to it for hours without being tired.

Dynamics is excellent. I mentioned above that the output voltage could need some boost when playing DSD. On my AHB2 amps, if connected directly to the amps, I would put the gain adjustment switch to medium when playing electronic music to get the necessary kick to move my B&W 802D3 at an appropriate level.

[SwissBear]

On 1/26/2021 at 10:12 PM, fmzip said:

Are you in the US? How long did shipping take? If I were to strictly use the I2s input, is it necessary to still order the upgraded version?

 

I am living in Switzerland. But shipment time should not be very different. I ordered on Thursday, the DAC was shipped on Friday, and was delivered Monday the next week. Shenzhenaudio uses the services of DLH Express.

 

Using the I2S input is a good idea. This allows to go up to PCM768 and DSD1024. I would like to mention that the integration of SDA-6 and SU-2 is excellent. With other DAC like the D90, I had very loud pops when changing sampling in HQPlayer. Together with SDA-6 things are very smooth.

 

Back to your question, the upgraded version offers Crystek clocks you will not benefit from, but you will still have the Mundorf capacitors at the output stage. We are not talking about fancy silver wirings here :-)

[SwissBear]

35 minutes ago, fmzip said:

Thanks for the info. What type of preamp are you using?

 

No preamp at this stage.

 

35 minutes ago, fmzip said:

NOS.....I read this but still am lost:

https://samplerateconverter.com/educational/nos-dac#:~:text=NOS DAC (non-oversampling DAC,oversampling vs non-oversampling DAC.

 

I am not using HQ Player with ROON;  is this feature still beneficial?

 

The idea of NOS is to make all the DSP tasks asynchronously outside the DAC. Therefore you have an exact control of the filter you are using, and the way your files are processed.

 

HQPlayer is a master in this art, and I warmly recommend you this software. If you have a preference to stick to Roon without HQPlayer, you can still use the NOS mode in making the upsampling inside Roon. You can also not upsample at all and use the NOS mode of the DAC to just process your files in their original format. I did not try this yet.

 

35 minutes ago, fmzip said:

They are showing DSD512, not 1024, on their website unless I am overlooking it. I've been using a Sonore UltraDigital for I2s and it's been working flawlessly as well

 

Yes, this is with the USB input. With I2S you can go up to PCM 768 and DSD 1024. DSD 1024 is not officially supported, so please don't tell anyone that I tried it, but still works :-)

 

[SwissBear]

Hi everyone,

 

We had an interesting discussion the other day with @Miska on the subject of 10 MHz clocks. I was trying to make the point that 10 MHz clocks had an interest in music reproduction which  Jussi refuted, explaining that the conversion of 10 MHz signal to frequencies usable by DAC oscillators (multiples of 44.1 kHz and 48 kHz) added jitter and was therefore not useful.

 

At the end of the discussion, Jussi shared some measurements of his Holo Spring 2 DAC, which were in fact not comparable to the ones I had published, essentially because he was measuring multiples of 44.1 kHz to show how powerful his technology of HQPlayer was in reducing jitter, when increasing sampling frequency to PCM 1.4 MHz or DSD 256. Measurement published by Jussi and mine were not comparable because the upsampling drastically reduces jitter, at least on his DAC and also because we had no idea of the number of samples used to make the FFT in either measurements, which has a direct impact on the noise floor.

 

To come back to my point, and to the comparison of things which are comparable, here is a graph of the jitter measured at the output of an R2R DAC, in connection with an interface SU-2. 

 

Please note that you cannot compare the noise floor with Jussi's measurement as we do not know how many samples were used to produce this FFT. Also, the impulse is at 12 kHz as the sampling frequency is 48 kHz. Please also note that the x-axis has been very much enlarged.

 

In red, measurement of the jitter induced by the oscillators of the SU-2 (Accusilicon AS-318B).

In blue, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is cold.

In green, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is hot (after 12 hours of warming).

 

 

I am tempted to infer from this graph that Yes, definitely, 10 MHz clock can have a beneficial influence on the J-test measurements of jitter, made at a DAC. I am also tempted to infer that Singxer has a good knowledge on how to implement these technologies.

 

Hope this helps :-)

 

Reference: http://www.erji.net/forum.php?mod=viewthread&tid=2216213&page=1#pid33553664

 

[EDIT] Measurements have been made by l7audiolab.com (https://hv6mkka65l5nbcgw64taospppe--www-l7audiolab-com.translate.goog/f/tmmt再出发/). The 10 MHz clock was Gustard C-18. 

[SwissBear]

35 minutes ago, SwissBear said:

Hi everyone,

 

We had an interesting discussion the other day with @Miska on the subject of 10 MHz clocks. I was trying to make the point that 10 MHz clocks had an interest in music reproduction which  Jussi refuted, explaining that the conversion of 10 MHz signal to frequencies usable by DAC oscillators (multiples of 44.1 kHz and 48 kHz) added jitter and was therefore not useful.

 

At the end of the discussion, Jussi shared some measurements of his Holo Spring 2 DAC, which were in fact not comparable to the ones I had published, essentially because he was measuring multiples of 44.1 kHz to show how powerful his technology of HQPlayer was in reducing jitter, when increasing sampling frequency to PCM 1.4 MHz or DSD 256. Measurement published by Jussi and mine were not comparable because the upsampling drastically reduces jitter, at least on his DAC and also because we had no idea of the number of samples used to make the FFT in either measurements, which has a direct impact on the noise floor.

 

To come back to my point, and to the comparison of things which are comparable, here is a graph of the jitter measured at the output of the SDA-6, in connection with an interface SU-2. 

 

Please note that you cannot compare the noise floor with Jussi's measurement as we do not know how many samples were used to produce this FFT. Also, the impulse is at 12 kHz as the sampling frequency is 48 kHz. Please also note that the x-axis has been very much enlarged.

 

In red, measurement of the jitter induced by the oscillators of the SU-2 (Accusilicon AS-318B).

In blue, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is cold.

In green, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is hot (after 12 hours of warming).

 

 

I am tempted to infer from this graph that Yes, definitely, 10 MHz clock can have a beneficial influence on the J-test measurements of jitter, made at a DAC. I am also tempted to infer that Singxer has a good knowledge on how to implement these technologies.

 

Hope this helps :-)

 

Reference: http://www.erji.net/forum.php?mod=viewthread&tid=2216213&page=1#pid33553664

 

A precision: the test is made with an R2R DAC and not the SDA-6 as this is made clear in the Chinese post :-)

[SwissBear]

3 hours ago, w1000i said:

Aha, yah that make sense as SDA-6 by it self has better measurements.

https://www.l7audiolab.com/f/measurementreview-of-singxer-sda-6/

 

 

You can only infer that if you know exactly the measurement conditions. The noise floor is a direct function of the number of samples used to build the FFT (FFT gain). So until you know that l7audiolab and Singxer have used the same number of samples, you can not compare the measurements. At least this is what I understand...

 

This is also a reason why it was useless to compare with Jussi's measurements...

 

I corrected this in my post. Thanks to Chris :-)

[SwissBear]

A few listening impressions from this week:

- the DAC has progressed very well since I received it early this week: it has been sounding more and more natural by the day

- the I2S input through SU-2 seems to offers slightly more galvanic isolation than USB input in my opinion. 

When connected directly to the output of a computer (NAA for HQPlayer), I have a preference for the SU-2 -> I2S -> SDA-6 solution. The piano keys of Claudio Arrau are flowing very naturally... 

When connected through another device, like SOtM tx-USB, both inputs (USB or I2S through SU-2) are on par. USB might be slightly more detailed, probably due to the clock signal being applied directly at the DAC... and highs through the I2S slightly more silky. Just a matter of taste and the possibility to adjust according to each piece of music.

- finally, I have a preference when the NAA is fed through my EtherRegen switch, which clock signal is given by my REF-10. 

This seems to further enhance the naturalness of the music flow.

I am very impressed by this new DAC :-)

 

[SwissBear]

2 hours ago, pavlos said:

@SwissBear, I think you are the very first consumer in the whole Internet posting private and objective opinion on this SDA-6 DAC. Finally! Thanks!

 

I am looking at his equipment, but had not found any review or opinion so far. Just some measurements, but measurements won't tell anything about sound quality and taste. And this is what I am looking for. Unfortunately there is no reseller in Poland (the closest is in the Netherlands), so I can not borrow it to check it in my system...

 

You are comparing its sounding with Matrix X-Sabre and Topping D90 - this is quite informative. I have also checked the D90, but I agree with your observation - it sounds a bit matt and flat even when comparing to a much cheaper Chinese ESS 9038Q2M-based DAC. So I have excluded D90 from my short list.

 

The question: have you ever tried Mytek Brooklyn Bridge/DAC+? Because this is currently on the top of my private list, upper than Chord Qutest (too shiny and randy). Mytek Brooklyn uses ESS 9028Pro chip. This is why I think it might be somehow close to the Matrix box.

 

My system has a velvet but also a bit dark sound, with high resolution - signature of my Vienna Acoutstic Beethoven loudspeakers. I wonder how the SDA-6 DAC would fit.  Maybe the ESS-based DAC could be better choice?... Now I tend to exclude any of AKM-based DACs, have also listened to Cary Audio 200-ts DAC, which is fantastic piece of equipment (especially with the tube output stage), but wouldn't fit to my system (too dark sound in the end).

I would appreciate any of your thoughts...

 

Hi @pavlos,

 

Thanks for your questions. You are touching one of the subjects where it is very difficult to advise: the aesthetic of the sound produced by the DAC... Not knowing your tastes and qualities of your systems, this is difficult for me to comment...

 

I tried to describe the sound produced by the SDA-6 as transparent, ie less bright than the ESS implementations I have listened to, and less matt than other AKM implementations.

 

Having said that, as @w1000ipointed out, Singxer has produced a well designed output stage, which sounds very well IMHO. You can also look at the tests and appreciations of their headphone and preamp SA-2 to get a better understanding of their capabilities in the field of analog design.

 

They have also shown their mastering of signal processing and FPGA programming in the development and production of their SU-2 interface, which is able to perfectly use the signal of an external master clock at 10 MHz to improve the performance of the jitter of the DAC they attach to it. If you are sensitive to the micro structure of music, this is a very important point as this would allow you in future to complement your system with such a high precision clock and enjoy even more details if this is what you are looking for. A good illustration of this capability is the ability of the combo SU-2 + SDA-6 to process DSD 1024 files produced by HQPlayer without any problem. With the D90, I was limited to DSD 256, as the I2S flow was going through the PLL in the DAC... On the x-Sabre, I am able to process DSD 512, but not DSD 1024 in the same conditions (SU-2 + x-Sabre).

 

Another topic which was important in my choice was the NOS mode (and the capability it gives to the DAC to process the files you are sending in a bit-perfect mode, without altering them before the D->A step).

 

So depending on your expectations, there are, in my opinion, many subjects where the SDA-6 scores better than its competitors.

 

Best thing would be for you to test and to listen with your own ears. In case you order from Magna Hifi in the Netherlands or Audiophonics in France, you will not have to pay customs and you will have 15 days to decide if you want to keep the machine or return it. This might be the best option for you.

 

Hope this helps :-)

[SwissBear]

5 minutes ago, pavlos said:

 

And Mytek Brooklyn DAC+ also has external clock input, by the way...

 

It seems that the clock input of the Brooklyn DAC+ is a World Clock and not a Master Clock.

The World Clock is intended at synchronising multiple instances of the DAC in order to process more than 2 channels.

You will probably have to convert the signal of any 10 MHz clock into a World Clock signal (multiple of 44.1kHz or 48kHz) in case you want the Brooklyn DAC+ to be used as slave...

That's what I understand from their user manual anyway :-)

[SwissBear]

On 2/1/2021 at 6:30 PM, Miska said:

Now let's see same test with SDA-6 Pro version with the Crystek CCHD-957 clocks vs the Mutec (?) 10 MHz external clock you are using...

 

Hi Jussi, 

Thanks for stopping by. I would love to make those measurements and contribute to a better scientific understanding of the influence of 10 MHz clocks on the behaviour of audio systems, independently of the marketing discourse of suppliers.

Unfortunately, this will not happen at this stage as I have not been able to convince myself that this was part of my hobby to invest into costly measurement devices.

Access to gears such as APx555B is limited, and the local reseller even refuses to rent me one as I am not a potential buyer :-) And the guys from Spectral Measurement didn’t even reply to my RFQ :-)

Another reason why this will not happen is that, despite the efforts put by Singxer into the galvanic isolation of their SDA-6, the USB input is by far not at the level of the I2S one, and I very much prefer to stay with the SU-2 interface in front of it.

So I will stay with the measurements which have already been published above, which show that the input of a 10 MHz OCXO clock into the SU-2 improves the jitter in quite a substantial manner, compared to its own Accusilicon AS-318B oscillators.

 

[SwissBear]

33 minutes ago, w1000i said:

I saw Singxer SU-6 has CRYSTEK’s CCHD-957 and a Clock output. So can that be connected to SDA-6 and is that better than a standalone clock ?

 

Well, the SDA-6 Pro has the same oscillators on its USB input. So I don't think that this SU-6 would improve things in terms of clock. It could obviously improve things in terms of galvanic isolation though. But I would personally favour the SU-2 which is cheaper for this purpose, and add an OCXO at 10 MHz. Prices for such 10 MHz clocks start around 100 USD on the Chinese market. As you can gradually improve the quality of this external clock if you see fit, until you are satisfied... Just be careful if you follow this path to chose a clock which has a 50 Ohm impedance output, as this is what the SU-2 is expecting, and to chose an RG-58 cable with BNC terminations.

Pasternack has some industrial ones in the US. Magna Hifi also has some in Europe.

Lots of discussions about 10 MHz clocks there: just be aware that EtherRegen expects 75 Ohm connexions though... 

 

[SwissBear]

5 hours ago, luisma said:

Thank you @SwissBear for posting, this looks like an interesting AKM DAC to be used with HQPe

 

The SDA-6 Pro alone will allow PCM384/DSD512, with the SU-2 you could go to PCM768/DSD1024

 

I was evaluating getting the RME ADI-2 (AKM 4493?) and multichannel with low resolution and this just gets me thinking it could be a better option, granted no bell and whistles like the ADI-2 but for HQPlayer looks very attractive

 

I think I would skip on the SU-2 though ... and a little more will get you a Spring 2

 

So many choices...

 

Thanks again

 

 

Thanks to you @luisma. It’s very joyful for me to notice how many new DACs now have this same NOS feature as SDA-6 and Holo range. To name a few recent releases, Gustard X-16 and X-26 Pro also do. I see this as the acknowledgement of the interest of HQPlayer and its asynchronous up sampling model :-)

[SwissBear]

2 hours ago, w1000i said:

SDA-6 alone in NOS can accept DSD1024 ? And what is the highest PCM in NOS.

 

As detailed in the specs, SDA-6 supports PCM 384 and DSD 512 through its USB port. Together with SU-2, it supports PCM 768 and DSD 1024. Both are supported in NOS.

[SwissBear]

19 minutes ago, R1200CL said:

Can you confirm clock impedance input for the DAC ?

 

If I got the Chinese correct translated, Singxer says the DAC will perform better with an external clock. 
 

I was not able to create a user there, as they require a Chinese cell number. (Witch I actually could fix, but it’s not that important to join). 
 

 

 

The clock input impedance of the SDA-6 can be adjusted to 50 or 75 Ohm. For the SU-2 it is 50 Ohm only.

[SwissBear]

25 minutes ago, R1200CL said:

This was related to the SU-2 or the SDA-6, or both ?

 

Would in any case be interesting to see measurements (if it make sense) with external clocks. Even the $92 cheap one.

 

As an SU-1 modified owner, I may be interest in SU-2 due to clock input. I will only use AES out.

Did you own a SU-1, so some sort of compares is possible?

Can external 5V be applied?

 

The discussion with Jussi was related to external 10 MHz clock inputs in general.

A measurement of a cheap OCXO at the input of an SU-2 has been posted above.

It's not strictly "external" 5V. But a friend of mine opened his SU-2 and applied 5V. Seems easy to do.

I do not have any experience with the SU-1. I compared the SU-2 to my MC-3+ USB in AES and I have a preference for the MC-3+ USB. I found it more transparent. I did not notice any lack of transparency of the SU-2 in I2S mode though.

 

Quote

Would you know main difference between SU-1/2 ? (Except clk in)

 

Do you know if square wave would be preferable?

(If you’re in contact with Singxer). 

 

For clock applications, there seems to be a concensus that square waves are preferable. I did not discuss that specifically with them, but you can contact Singxer. The email address of Leter is on their web site.

[SwissBear]

8 hours ago, etane said:

How does SDA6 compare to D90/SU2??  I am currently using D90MQA/SU2 and find it very listenable especially with Sikai branded HDMI cable found on amz. D90MQA sounds very good but a bit flat and narrow.  SU2 fixes these and am spoiled by the amount of air around the instruments now.  But, you claim SDA6/SU2 is even better.  So, got me curious.

 

 

Hi,

My experience with D90/SU-2 was hectic. Combined with HQPlayer, this setup was producing large clicks/pops when changing formats or sample rates. This damaged one of my tweeters so I had to send the D90 back.

Apart from that, I noticed a presentation of the sound which was vey detailed, but a little bit matt for my taste, as much as the x-Sabre/SU-2 was very detailed but a bit bright for my taste. The SDA-6/SU-2 is right in the middle, just transparent sound-wise.

A lot of air and instruments separation too, whether the SDA-6 alone or in connexion to the SU-2. I have a slight preference for the SU-2 connexion as it seems to offer a little more darkness, airiness and separation in my system.

The SDA-6 alone seems a little more detailed though.

Hope this helps.

 

[EDIT] I would add to this that the D90 is using its PLL when fed through I2S. This limits the usage of DSD to DSD256. When using an SDA-6, you can go up to DSD1024 or PCM768 is you see fit.

[SwissBear]

On 2/17/2021 at 12:48 PM, w1000i said:

Any thought of how HQplayer perform with this DAC in NOS ! Does the setting change in HQplayers results in more SQ change compare to other DAC if somebody did compare or have long experience with HQP.

:) 

I guess it will be interesting to read the listening report from @patatras when he finally gets his SDA-6. He still owns another DAC he is very happy with, and has a very good installation with Roon+HQPlayer+Diretta as well as very well trained ears, as he has received a classical music education and taught music himself.

Wait and see what he thinks about HQPlayer filters and NOS mode of AK4499 :-)

[SwissBear]

26 minutes ago, pavlos said:

Hi All,

 

I think I owe you some information about the result of my race for a DAC, where I was considering Singex-SDA-6.

Due to lack of any Singex resellers in Poland I have finally given up ordering from abroad and have walked through available supply in my market - within my budget (<=2kEUR). Six species invited and listened at home, in my system. One-by-one.

 

And the winner is: DENAFRIPS Pontus II.

 

The most clear, clean, defined, rare and precious sound.

Not clinical (ESS tendency), not soft or lifeless (AKM tendency), not artificially overcolored (Chord).

Not any of D/S chip based DACs, not FPGA-based, but this R2R construction.

 

As a matter of fact I didn't have the chance to check the cheaper Musician Audio Pegasus, also gathering only good if not enthusiastic opinions.

 

Well, Pontus is equipped with I2S input, so maybe one day I will come back to Singex label for a higher quality of USB interfaces, as all of you share only the best opinions about their devices.

 

So, keep healthy and have fun!

 

pavlos

 

See here:

 

 

Hi Pavlos,

Congratulations on your choice. Happy listening with your new DAC :-)

[SwissBear]

6 hours ago, R1200CL said:

Got an SU-2. Not connected yet. Just on power. Should equal burn in. 
One guy told me an USB to SPDIF converter can’t use or benefit from an external 10Mhz clock. 
 

Makes me wonder where this external clock is used in the SU-2. 

 

The goal of the SU-2 is to convert an USB flow, which is asynchronous, into SPDIF or I2S, both of which are synchronous music flows, which embark music data together with a clock signal. So connecting a high precision clock to the SU-2 will allow the output flow to be clocked by this high precision clock.

In case your DAC follows the clock signal included in the SPDIF or I2S flow, you will benefit from this high precision clock signal.

This is the case of the SDA-6 which is mentioned here.

[SwissBear]

33 minutes ago, hopkins said:

Some explanations are provided here in response to the measurements you also posted on ASR: 

 

https://www.audio “science” review/forum/index.php?threads/singxer-sda-6-influence-of-a-10-mhz-clock.19922/

 

There are also some who claim that the precision of the clock is not the issue, but all the RF going on inside the DAC (especially when inputting high bandwidth signals as USB, I2S, SPDIF...).

 

You can understand there could be some skepticism about all this, (and the cost of a REF-10 at 4000€ is significant).  This begs one question: have others done this aside from you or are you just relating your own "in house" experimentation ? Did anyone actually listen to your setup (SDA6 with and without the REF-10) aside from you ?

 

Skepticism is welcome. The reactions on the other forum you mentioned was not skepticism, but dogmatism IMO.

 

There are some high level DAC manufacturers who believe that high precision clocks are part of the game of rebuilding a decent analog signal from digital audio. Here are some examples:

https://www.dcsltd.co.uk/products/rossini-clock/

https://www.ch-precision.com/product/t1-10mhz-time-reference/

 

My intention in this thread is to show that there is no need to go for such expensive solutions and that one can find cheaper alternative in case on is sensitive to such benefits.

 

As already explained about Diretta and its benefits, not everyone is sensitive to the effets of precise clocking.

You might not be interested or skeptic. This does not make the subject irrelevant for others.

[SwissBear]

7 hours ago, hopkins said:

Thanks for all this, but you did not answer my question (and I did not say this was uninteresting!).

 

BTW I also think timing is key, the question is how to achieve it...and how to make sure percieved changes are consistent, shared by others, and isolated (cannot be attributed to other factors). 

 

It’s quite easy to organize blind tests in this matter. Turning the clock outputs on and off is easy and the front end of the clock itself can be hidden with a carton sheet.

 

I did this several times with my wife and with audiophile friends on a one to one basis with the same unequivocal results. The presence of the clock signal was detected and highlighted.

 

I could not make double bind tests due to sanitary restrictions though. And I doubt I will make any in the future, as I am not making scientific claims which would deserve such organization.

[SwissBear]

7 hours ago, R1200CL said:

Can’t say how my old Theta Generation VIII deal with AES/EBU. I taught it could only be one way ?

if you already own the SU-2, you are not far from getting the answer though. You can just find an AES/EBU cable and listen for yourself.

[SwissBear]

2 hours ago, R1200CL said:

Yes, of cause. I probably didn’t understand your first answer. 

 

As there are DAC’s that don’t benefit from the clock signal included in the SPDIF. 

 

I'm not sure. What I noticed with my experience with I2S is that the inability of some DACs to not use their PLL was making the use of an external clock less productive. But with AES/EBU, PLL seems to be necessary as we need to correct for the jitter introduced by the cable if I'm correct.