Douk Audio U2Pro Digital Interface Upgrade is Being Planned and Waiting for Your Advice!

[Roland68]

Hi thank you very much for your kind and valuable advice.
I had to ask because some time ago I read a review of a USB to SPDIF/AES_EBU converter that, according to the experts, was pretty much the best for its time... from Berkeley Audiodesign Company, shown below.

Alpha USB Series 2 — Berkeley Audio Design

www.berkeleyaudiodesign.com

Obviously, among other things, it also reclocked the input signal and output it very precisely.
Well, at a certain point, the reviewer said he'd tried the unit with different sources like a PC, CD player, DVD player, etc., of different prices and therefore quality.
And he claimed that the differences in sound were so small they were difficult to perceive.
This has always fascinated me.
And I wonder if such performance is now offered at lower prices. I certainly don't have a system that justifies spending so much on a component. I'm not a purist who thinks it's DSD or nothing. i like just decent sound.
Thanks again and best regards, Gino

For me, such devices are just modern-day gimmicks, and the price is absolutely ridiculous.
There are no relevant measurements, no real tests with results from an AP unit.
Why not?

If you believe that an external DDC can do more than what's built into a modern €300 DAC, then you've really been taken in by these people.
I've tested several DDCs over the past few years, including some in similar price ranges, and the differences were marginal at best compared to current DACs, and sometimes even worse.
DDC technology was already used in DACs years ago and has been further developed and perfected by DAC manufacturers ever since.

Take a look at the reviews by user @NTTY on the SMSL D200, the Clock G1, the two CD players/transports PL200 and PL200T, and several other CD players.
Many DACs and DDCs that cost many times more are inferior. Even a €79 DAC like the SMSL D1 ROHM DAC is so good that it has replaced one of the best-measuring DACs in the €500 class for me.

 

[gino1961]

thanks a lot again for the precious advice
What i really do not like of cheap dacs is that they take power from the pc via usb weak dirty dc ... unacceptable
i am little confused about the different inputs I am using a pc as a source
So if i want to send an spdif signal to the dac i have to use optical or coaxial Then i need a converter like the ones mentioned in this thread i will have to think a little more
i like the idea of a converter because i have other dacs to try out Most of them without usb inputs

 

[Perpetual Novice]

In addition to my previous post, I did a little more digging and managed to find a couple of compatible oscillators that Douk customer service said would work:

"Hello, Many thanks for the help. Given the specs that have been provided above I was wondering if either of these oscillators would suitable for use in the U2 Pro.
ASFLMB-24.000MHZ-XY-T (10PPM): https://nz.mouser.com/ProductDetail/ABRACON/ASFLMB-24.000MHZ-XY-T?qs=CnD89xF1VSkLeoJKBbCF%2BA==

or the TG2520SMN 24.0000M-ECGNNM0 (0.5PPM): https://nz.mouser.com/ProductDetail...-24.0000M-ECGNNM0?qs=4qgZ1GHix0X2daxyp10DGQ==

Douk Audio Customer service:
Hi, both oscillators are compatible with the U2 PRO."

For the record I'm not at saying that these are the best options, this is just what I was able to stumble across with my noob knowledge. They are quite affordable and in line with the fact that I only paid $57 USD for the U2 Pro.
Based on the specs (TCXO, 24 Mhz, 1.8v), if anyone has any better suggestions I'd appreciate it. My sincerest thanks in advance.

 

[Schlippwhip68]

Hello! I'm new here and a complete noob. I came across this thread looking for info around upgrading the clock. I had an online chat with Douk Audio Customer Service a few days ago. I thought it could be possibly be helpful, apologies if it isn't.

"Hi, to replace the original crystal oscillator, the specifications must be 24MHz/1.8V. The parameters of the oscillator from the link you shared differ too significantly from the original, so we do not recommend using it...We will soon be launching new versions of the U2 PRO: a TCXO version and a Femto-second version. You may want to consider these for a future upgrade...If you decide to replace it yourself, we suggest you choose a high-precision, temperature-compensated crystal oscillator."

That's all I've got, sadly i don't have any further info and I'm unqualified suggest any potential replacements. Hope this helps a little in any case.

Perhaps @Douk Audio can expand further?

The Crystek 957 seems to be a popular choice for many people. I am looking into this myself.
If this is in the chain ie sitting between the PC and Dac then the signal is going to be cleaner, more organised before it even reaches the da. Even when the dac already has a good clock this MAY improve the sound with more uniform in the 0 and 1’s. Less work for the dac…theoretically. I have one arriving today and will see if this theory proves anything.

Which model are Douk upgrading as they have only just released the 2025 U2 Pro. It seems very early to upgrade it.

 

[Schlippwhip68]

In addition to my previous post, I did a little more digging and managed to find a couple of compatible oscillators that Douk customer service said would work:

"Hello, Many thanks for the help. Given the specs that have been provided above I was wondering if either of these oscillators would suitable for use in the U2 Pro.
ASFLMB-24.000MHZ-XY-T (10PPM): https://nz.mouser.com/ProductDetail/ABRACON/ASFLMB-24.000MHZ-XY-T?qs=CnD89xF1VSkLeoJKBbCF%2BA==

or the TG2520SMN 24.0000M-ECGNNM0 (0.5PPM): https://nz.mouser.com/ProductDetail/Epson-Timing/TG2520SMN-24.0000M-ECGNNM0?qs=4qgZ1GHix0X2daxyp10DGQ==

Douk Audio Customer service:
Hi, both oscillators are compatible with the U2 PRO."

For the record I'm not at saying that these are the best options, this is just what I was able to stumble across with my noob knowledge. They are quite affordable and in line with the fact that I only paid $57 USD for the U2 Pro.
Based on the specs (TCXO, 24 Mhz, 1.8v), if anyone has any better suggestions I'd appreciate it. My sincerest thanks in advance.

I don’t think either one of those will improve much on what’s already in the U2 Pro. They will match very well but again I am sceptical as to any improvement.
You may need to aim a little higher.

 

[MCH]

In addition to my previous post, I did a little more digging and managed to find a couple of compatible oscillators that Douk customer service said would work:

"Hello, Many thanks for the help. Given the specs that have been provided above I was wondering if either of these oscillators would suitable for use in the U2 Pro.
ASFLMB-24.000MHZ-XY-T (10PPM): https://nz.mouser.com/ProductDetail/ABRACON/ASFLMB-24.000MHZ-XY-T?qs=CnD89xF1VSkLeoJKBbCF%2BA==

or the TG2520SMN 24.0000M-ECGNNM0 (0.5PPM): https://nz.mouser.com/ProductDetail/Epson-Timing/TG2520SMN-24.0000M-ECGNNM0?qs=4qgZ1GHix0X2daxyp10DGQ==

Douk Audio Customer service:
Hi, both oscillators are compatible with the U2 PRO."

For the record I'm not at saying that these are the best options, this is just what I was able to stumble across with my noob knowledge. They are quite affordable and in line with the fact that I only paid $57 USD for the U2 Pro.
Based on the specs (TCXO, 24 Mhz, 1.8v), if anyone has any better suggestions I'd appreciate it. My sincerest thanks in advance.

What is the problem you are trying to solve?
If none, don't change anything. You are not going to improve anything and you risk destroying your unit.
How do you plan to solder it? Those parts are relatively easy to solder but they are often very close to other parts.... unless you have some skills with smd soldering, I recommend you not to even attempt it.
Besides that, the two parts you linked are not the same size. Have you measured the original one?

 

[Roland68]

thanks a lot again for the precious advice
What i really do not like of cheap dacs is that they take power from the pc via usb weak dirty dc ... unacceptable
i am little confused about the different inputs I am using a pc as a source
So if i want to send an spdif signal to the dac i have to use optical or coaxial Then i need a converter like the ones mentioned in this thread i will have to think a little more
i like the idea of a converter because i have other dacs to try out Most of them without usb inputs

You should free yourself from all this nonsense. You're chasing after things that don't (or no longer) exist and make no difference.
Powering DACs via USB is a long-since-solved problem with modern and well-tested DACs. Besides, you can also equip any USB-powered DAC with a dedicated power supply. The D1 even has an additional power connector for this purpose.

The most direct path from your PC to the DAC (chip) is:
USB cable → XMOS interface → I2S transmission to the DAC chip.

Do you really think it will be better if you take detours via additional devices (DDCs) and perform unnecessary conversions of the digital signal?
USB cable → XMOS interface → I2S → conversion to SPDIF/Toslink → external optical transmission to the DAC → conversion from SPDIF/Toslink to I2S → transmission to the DAC chip
Since the DAC chip typically receives the digital signal as I2S, this also applies to all other interfaces such as AES/EBU, I2S over LVDS, SPDIF/Coax, etc. Additional external transmission of the digital signal and conversion/re-conversion is completely unnecessary and pointless.

The only exception is ground problems that lead to audible interference. In this case, galvanic isolation of the signal via optical transmission is a good solution.
This can be achieved for €25-100, for example, with a USB to Toslink adapter or with DDCs such as the Douk Audio U2 PRO, SMSL PO100, PO100 PRO, and PO100AK, the latter of which also includes a very good AK4493 DAC.

 

[Roland68]

Which model are Douk upgrading as they have only just released the 2025 U2 Pro. It seems very early to upgrade it.

As @Petual Novice mentioned above, Douk Audio is releasing new/additional versions of the U2 PRO with TCXO and femtosecond crystal oscillators.
These are already listed with prices on the Douk Audio website.

 

[gino1961]

You should free yourself from all this nonsense. You're chasing after things that don't (or no longer) exist and make no difference.
Powering DACs via USB is a long-since-solved problem with modern and well-tested DACs. Besides, you can also equip any USB-powered DAC with a dedicated power supply. The D1 even has an additional power connector for this purpose.

Hi thanks a lot again I would not want to overload the usb bus on the pc And actually i see that some dacs come with two usb inputs ... one for data and DC and one only for DC like the SMSL Sanskrit 10th MK II i also have and like
there must be a reason i guess

moreover i tend to use the optical link to get some kind of electrical isolation from the source

The most direct path from your PC to the DAC (chip) is:
USB cable → XMOS interface → I2S transmission to the DAC chip.
Do you really think it will be better if you take detours via additional devices (DDCs) and perform unnecessary conversions of the digital signal ?
USB cable → XMOS interface → I2S → conversion to SPDIF/Toslink → external optical transmission to the DAC → conversion from SPDIF/Toslink to I2S → transmission to the DAC chip
Since the DAC chip typically receives the digital signal as I2S, this also applies to all other interfaces such as AES/EBU, I2S over LVDS, SPDIF/Coax, etc. Additional external transmission of the digital signal and conversion/re-conversion is completely unnecessary and pointless.
The only exception is ground problems that lead to audible interference. In this case, galvanic isolation of the signal via optical transmission is a good solution.
This can be achieved for €25-100, for example, with a USB to Toslink adapter or with DDCs such as the Douk Audio U2 PRO, SMSL PO100, PO100 PRO, and PO100AK, the latter of which also includes a very good AK4493 DAC.

Perfect ! i will try a Douk Audio U2 PRO soon Yes i like toslink the better I have already a decent cable
i remember i read something about the use of a gel on terminations ... to avoid the air gaps But i have not experienced loss of signals ever
no need to fix what is not broken i guess
i will get a Douk Audio unit and be done with that
Have a nice day
gino

 

[Schlippwhip68]

As @Petual Novice mentioned above, Douk Audio is releasing new/additional versions of the U2 PRO with TCXO and femtosecond crystal oscillators.
These are already listed with prices on the Douk Audio website.

View attachment 489315View attachment 489316

Ooph! The Femto version is pricey, especially for a product that has some serious doubt as to any actual real time improvements over today’s dacs.

My ‘standard’ version has arrived now so I am going to test this with the Topping E50 and iFi Zen One Signature dacs.
Will tell you if I hear anything where it was heard not before….

 

[Schlippwhip68]

Ok, positive results! It does perform in the way I expected it too.

Pros:The sound of the E50 is cleaner, more organised, less boom in the bass, tighter frequency response, vocals are notably more precise with more solidity as to position, less fruit salad more fruit rack, more natural sounding too. Cleaner more extended highs. Better depth to the soundstage.

The Topping E50 has a xmos 216.

Cons: Possibly cable fussy. Works with the Fiio usb c to c cable but not with another cable that I ordered specifically. I think this maybe down to the cable and not the U2.
Slight volume drop, there is an louder direct usb connection from the PC to the Dac. Not a deal breaker by any means but something to be aware of.
It’s bit of a gas guzzler to start off with but power draw stabilised over a hour and so not an issue for battery power as initially thought

Conclusion: I think it’s worth keeping in the chain. It acts like a Sergeant pulling his troops into line before parade and it does it well before they are seen by the General in this case the Dac.
The new upgraded versions, pricey though they maybe will probably improve things even further but then so would upgrading the standard version with the correct clock ie 24mhz TCXO which if you have the skills, will be cheaper. The result straight out of the box is notable. Personally I like what this does with the vocals best, seems to lock them down and in protecting them from any overlapping from surrounding instrumentation. It is certainly squeezing a bit more out of the E50, the treble is a little more surgical especially on some House tracks where it’s a predominant frequency.

This is good to be honest and for a standard version, bass- tight and punchy, more rounded, more sure of its own character and position, cleaner hits on the drums. Far greater precision. Cleaner reverb and decay too and very noticeable when listening to more atmospheric musical constructions. My Q Acoustics 3020i are not hiding anything here but have allowed the improvement arrangement to come through with ease so what the 5020’s will do or even their new 3030c speakers will certainly impress.

As far as upgrading the standard goes, that is tricky imo. It’s quite a bit of pro work there and this already sounds good but nevertheless it’s an open unit and I still prefer to have the option.

One thing I am not sure on is using a usb splitter cable. If it were possible then powering the U2 with an Ifi Power X 5v undoubtedly would bring cleaner power to this wee box but I am not sure where the draw of needed power is given priority, if it is usb, then it’s an pointless venture. It is a head scratcher with no measuring equipment.
Any confirmation on this particular mystery is very welcome.

So the sound quality in a nutshell….well it’s gone from mmm yeah ok I might switch op amps tomorrow to…struggling to take the dog out for his walk…and op amps have not come into it, that’s good, though the doesn’t seem to think so.


Nice one Douk Audio, I didn’t think I would get any further with it over the already capable Topping E50 but I stand happily corrected.

 

[Roland68]

Hi thanks a lot again I would not want to overload the usb bus on the pc And actually i see that some dacs come with two usb inputs ... one for data and DC and one only for DC like the SMSL Sanskrit 10th MK II i also have and like
there must be a reason i guess

View attachment 489320

Where does such misinformation come from? The USB port is overloaded by the DAC?
When you connect your phone or another battery-powered device, it immediately draws the maximum current, but a USB DAC that only draws 0.5-1.5 watts overloads the USB port? There are many devices that draw far more power from a USB port.

The usual reason for installing an additional power output in a USB-powered DAC is to allow it to be used with devices that aren't designed for it or where the operating time would be significantly reduced, such as phones, DAPs, tablets, etc.
Excerpt from the manual of the SMSL Sanskrit 10th MK/II:

 

[Perpetual Novice]

The Crystek 957 seems to be a popular choice for many people. I am looking into this myself.
If this is in the chain ie sitting between the PC and Dac then the signal is going to be cleaner, more organised before it even reaches the da. Even when the dac already has a good clock this MAY improve the sound with more uniform in the 0 and 1’s. Less work for the dac…theoretically. I have one arriving today and will see if this theory proves anything.

Which model are Douk upgrading as they have only just released the 2025 U2 Pro. It seems very early to upgrade it.View attachment 489301View attachment 489300

Cool thanks! I'll be curious to hear about your results.

 

[Perpetual Novice]

I don’t think either one of those will improve much on what’s already in the U2 Pro. They will match very well but again I am sceptical as to any improvement.
You may need to aim a little higher.

Great, thanks for that. I'm not in any rush so I'll keep looking.

 

[Perpetual Novice]

What is the problem you are trying to solve?
If none, don't change anything. You are not going to improve anything and you risk destroying your unit.
How do you plan to solder it? Those parts are relatively easy to solder but they are often very close to other parts.... unless you have some skills with smd soldering, I recommend you not to even attempt it.
Besides that, the two parts you linked are not the same size. Have you measured the original one?

I'm just looking to have a bit of fun and learn. It was really inexpensive ($57), so I'm taking the opportunity for a bit of DIY and the unit is designed for it. Its something that I enjoy doing when I can. The U2 pro is designed to take two different sizes, that's why Douk Audio customer service said that they would both work for the unit. Soldering won't be an issue, if i decide to switch it out.

Many thanks for your help and questions.

 

[Perpetual Novice]

Ok, positive results! It does perform in the way I expected it too.

Pros:The sound of the E50 is cleaner, more organised, less boom in the bass, tighter frequency response, vocals are notably more precise with more solidity as to position, less fruit salad more fruit rack, more natural sounding too. Cleaner more extended highs. Better depth to the soundstage.

The Topping E50 has a xmos 216.

Cons: Possibly cable fussy. Works with the Fiio usb c to c cable but not with another cable that I ordered specifically. I think this maybe down to the cable and not the U2.
Slight volume drop, there is an louder direct usb connection from the PC to the Dac. Not a deal breaker by any means but something to be aware of.
It’s bit of a gas guzzler to start off with but power draw stabilised over a hour and so not an issue for battery power as initially thought

Conclusion: I think it’s worth keeping in the chain. It acts like a Sergeant pulling his troops into line before parade and it does it well before they are seen by the General in this case the Dac.
The new upgraded versions, pricey though they maybe will probably improve things even further but then so would upgrading the standard version with the correct clock ie 24mhz TCXO which if you have the skills, will be cheaper. The result straight out of the box is notable. Personally I like what this does with the vocals best, seems to lock them down and in protecting them from any overlapping from surrounding instrumentation. It is certainly squeezing a bit more out of the E50, the treble is a little more surgical especially on some House tracks where it’s a predominant frequency.

This is good to be honest and for a standard version, bass- tight and punchy, more rounded, more sure of its own character and position, cleaner hits on the drums. Far greater precision. Cleaner reverb and decay too and very noticeable when listening to more atmospheric musical constructions. My Q Acoustics 3020i are not hiding anything here but have allowed the improvement arrangement to come through with ease so what the 5020’s will do or even their new 3030c speakers will certainly impress.

As far as upgrading the standard goes, that is tricky imo. It’s quite a bit of pro work there and this already sounds good but nevertheless it’s an open unit and I still prefer to have the option.

One thing I am not sure on is using a usb splitter cable. If it were possible then powering the U2 with an Ifi Power X 5v undoubtedly would bring cleaner power to this wee box but I am not sure where the draw of needed power is given priority, if it is usb, then it’s an pointless venture. It is a head scratcher with no measuring equipment.
Any confirmation on this particular mystery is very welcome.

So the sound quality in a nutshell….well it’s gone from mmm yeah ok I might switch op amps tomorrow to…struggling to take the dog out for his walk…and op amps have not come into it, that’s good, though the doesn’t seem to think so.


Nice one Douk Audio, I didn’t think I would get any further with it over the already capable Topping E50 but I stand happily corrected.

Thanks for this! Mine should be here either today or tomorrow, looking forward to popping it into the chain. Definitely something to look forward too.

 

[Schlippwhip68]

Thanks for this! Mine should be here either today or tomorrow, looking forward to popping it into the chain. Definitely something to look forward too.

Does a great job. Curious to find out which clocks Douk have used in their new models.

 

[Perpetual Novice]

Does a great job. Curious to find out which clocks Douk have used in their new models.

Mine didn't arrive today but should be here tomorrow afternoon. Really looking forward to hooking it up. I had the same thought today, hopefully they release that info.

 

[Schlippwhip68]

Mine didn't arrive today but should be here tomorrow afternoon. Really looking forward to hooking it up. I had the same thought today, hopefully they release that info.

Sorry to hear that, I can say this little piece of electronic engineering is what my system needed. I have gone through a few dacs over the years and always knew something was always just a little off with all of them. This has proved to be the elusive answer which leads me to believe there is a lot secrets in this field that are often kept.
Straightening those 0 and 1s up before they hit the dac is essential for good bass etc. I use a Windows PC for my source and an Fiio SR11 for when I am in need of a seat elsewhere.
Going to see if I can run the Fiio SR11 through it at some point and if I can then I just may get a better result with that too.

 

[gino1961]

Where does such misinformation come from? The USB port is overloaded by the DAC ? When you connect your phone or another battery-powered device, it immediately draws the maximum current, but a USB DAC that only draws 0.5-1.5 watts overloads the USB port? There are many devices that draw far more power from a USB port.

hi well i do not know the current draw at 5 VDC of a dac ... you mean that is about 300mA ? good i have seen some usb amperometer on amazon
maybe i could buy one and check to be sure

The usual reason for installing an additional power output in a USB-powered DAC is to allow it to be used with devices that aren't designed for it or where the operating time would be significantly reduced, such as phones, DAPs, tablets, etc.
Excerpt from the manual of the SMSL Sanskrit 10th MK/II:
View attachment 489346

thank you very much for the info Sorry but i still prefer to separate power supply and data lines because i have already a linear power supply that i could use for the 5VDC supply
But i would love one day to be able to run some measurements to check something Like noise jitter THD i am not very skilled so it is taking some time
Thanks a lot again