S.M.S.L PO100 AK - Measurements / Round 2 (DAC)

[ManniX]

Because if you're comparing a 2.1Vrms (what comes out the PO100 AK) versus, for instance, some 2.6Vrms output, then any listening comparaison is pointless. Almost everyone will (believe to) prefer the higher output, regardless of the real performance. Classic trick from many manufacturers to just have over "standards" output voltage for DACs/CD Players, or exaggerated Gain for amplifiers (which some regular audiophiles may translate into "more powerful", unless it is not).

I would have used to UMIK-1 and compared the SPL with REW.
But indeed with the DMM is probably better.
I thought it was only really relevant for the balanced output to measure the voltage

Is there a standard procedure?
Some specific kind of noise or test tone to use?

Yesterday I did some listening at a decent volume level. Not too long to avoid the neighbors come and chop me into pieces...
But the difference was even more noticeable at low volume. Maybe it's a sign there's a voltage output difference.

Isn't France also in Europe?

Oh la la, pardon moi.
I mixed up with someone else, sorry I'm getting old...
That's perfect, I'm in Germany, very close!

 

[ManniX]

Well. I have found a thread here discussing it (saint ASR).
Hope it's good enough.

I used a 500Hz and 1kHz test tone at 192 kHz output on ASIO; the PO100 AK gain set to 0db.

Unfortunately, it's definitely time to buy a scope
I've been delaying the purchase again and again.
This DMM is okayish for DC measurements, which is what I usually do.
But for AC only has 200V/500V so the resolution is pretty poor.

At 500 Hz the PO100 voltage is bouncing very erratically between 1.5V and 1.6V; sometimes almost steady at 1.5V, sometimes at 1.6V.
The X8 is steady at 1.5V.

At 1 kHz the PO100 voltage is mostly at 1.6V switching sometimes to 1.5V or steady at 1.5V.
The X8 is steady at 1.4V.

So it's quite the opposite as expected, the PO100 AK is "cheating" with a 0.1V boost.

Could be the PO100 voltage always ends in the threshold between the minimum DMM resolution.
But I have repeated the measurements at least 20-30 times, switching from one to the other.
The PO100 voltage output keeps changing, the X8 is always exactly the same.

Also this is the first time I feel a difference in DAC filters!
But unfortunately not in a good way
There are a couple of them, I forgot already which ones (the A-B-C-D LEDs are awful), which are definitely slightly worse than the rest.

 

[ManniX]

The big difference between the PO100 and the X8, as I suspected at the beginning, is definitely the different PCM decoding and/or filtering between the AKM and ESS DACs.

Did some A/B testing with 2 DxD albums this morning and the ESS is way better.
The AKM is way inferior than the ESS; maybe something is wrong in how it has been implemented by SMSL or maybe it's again the filter.
But I used DxD content at 352,8 kHz specifically to minimize the filter impact.

The X8 on "Wild Man Blues" from Bruels/Rigter Quintet felt better; more details and not "thin" like the PO100.

Then I've tested "Ray!" from Carmen Gomes', focusing on "CC Rider".
The difference in her voice is, in musical terms, just like night and day.
Once compared with the X8, on the PO100 is cold, a bit synthetic, and it stays in the background.
And it's the same every time, consistently and repeatedly.

I don't think it's just me, it's clearly much worse on the PO100.
Maybe I got a sub-par PO100 or maybe that's more than just the 8 kHz passband wrong on the AKM filter.

During the rest of the day I listened on the PO100 and the X8 my preferred Classical soundtrack for work, TACET's Vivaldi The Four Seasons in DSD.
I've listened it on the PO100 at least 2-3 dozens times the last 2 weeks.
I really love the execution and the recording, I know it very well now.

Suddenly the big gap between the PO100 and the X8 disappears...
I can say that sounds a tad better on the X8; again it's slightly more detailed, renders better the most complex parts and in general the soundstage on the PO100 is more backwards, in the background.
But it's a small delta that you can only spot if you really know very well the recording.

The 0,1V more on the voltage output of the PO100 is not noticeable at all.
Seems quite the opposite, the X8 surprised me more than once for the volume level.
Maybe it's "doped" to compensate the "thin" timbre?

I can say it's big win of the X8 over the PO100 but I wouldn't know against another 80€ DAC with the same ESS DAC.

Next will be testing the "opamp rolling" voodoo...
For this I decided to go straight with "the best"; I think it's the only chance for my old ear to spot any difference.
Ordered an SS3602 opamp from Audiophonics but it'll be shipped only after 30th of May.

 

[ManniX]

I can only blame myself for this, cause I should have checked beforehand the AKM and ESS datasheets...

The AKM DACs compared to ESS are total rubbish!

I wouldn't have ever imagined that a so acclaimed brand, used in so many expensive and high-end products, could be so bad.

From @VintageFlanker FR graph for the PO100 AK seems that it's exactly like in the datasheet:

Every fs rate has its own static configuration. And they are not even documented!

ESS is doing exactly what should be done (in my opinion), using parametric settings based on the fs.

Even in the worst case, the Linear Phase Slow Roll-off, the filter at 44.1 kHz in the passband range is between 15,7 kHz and 19,8 kHz.
For the old me it's already way out of the audible region; the only discerning factors are ringing and other artefacts with all filters.
Which is very good cause the AKM does impact heavily the FR and it's definitely worse than ESS.
Maybe someone likes it? I doubt it.

No wonder I can't pickup any difference between the filters...
I'll have to find some tailored content with percussions to use as test asset and then check again each filter one by one.

Anyway the parametric nature of ESS filters is not the only difference.
The AKM filters are not customizable at all.

Every ESS DAC, even the low-end models, can use one fully customizable FIR filter generated by MATLAB.
Not only this, they all support NOS mode (OSF bypass) with input rates up to 1,5 MHz.

I really wonder why only very expensive DACs have a NOS mode. It should be available also on 80€ DACs...
I can understand that a custom filter is not an easy task but NOS mode should be trivial.

In summary, the ESS DACs are by far more advanced than AKM and there's no justifiable reason why is that for me.

@VintageFlanker
I picked a Siglent scope; it's more capable for audio stuff than the Rigol. It should arrive next Tuesday.
But the UI is quite problematic and I'm not familiar at all with it.

Will try to compare something, not sure yet what and how, between the X8 and the PO100.
I guess the unstable voltage from the PO100 should be easy to spot.

When I'll get this amazing SS3602 op-amp will also try to measure the X8 with the other 2 op-amps which are coming with it.
Is coming from Audiophonics so it'll be probably delivered end of next week.
I assume that if there's an audio quality difference and it's not picked with an audio analysis, should be visible somehow with a scope.

Not sure again what to try but it'll be fun trying to.
If you have suggestions, let me know.

 

[ManniX]

Today just after calibrating the scope probes, I started testing the PO100 AK/Aune X8 line output.

Just a simple test to check the messy voltage reading from the PO100 with the DMM.

The initial results were quite the opposite as expected... the Aune X8 voltage was randomly dropping to low levels.
I started investigating the finnicky coupling between the probe leads and the cable and indeed the contact was not that good.
But the problem persisted, switching to the PO100 no issue while the X8 was randomly collapsing.
At that point I started suspecting something was wrong with power supply. And indeed that was the culprit...

Since the X8 is lacking basic features like an RCU, an IR sensor and even a 12V trigger, mine is connected to the switched AC plug of the amp.
This thing is very old and it seems that sometimes the AC is polluted with noise.
The moment I moved it to the power strip, the problem went away.
Moved it back to the same amp AC plug and now it works fine...

Well, now I understand why Aune is recommending the hefty price 109€ linear PSU.
And there are people reporting that it helps.
Clearly, despite being quite a big brick, the DC input section is very inefficient in filtering noise.
Not fancy at all considering the total cost of this unit would be 354€ + 109€ = 463€
Bit too much expensive considering the offer.

Seems to be a good ide to ask someone with a scope or a high-end DMM to verify the line out of the DAC.
This problem wasn't creating audible distortions, at least to me, and probably would have been very hard to sport with an ADC.
The drops were so quick that probably would have been hidden in the noise.

I tested with 192 kHz test tones on ASIO outputs at 50, 500. 1000, 12000, 17000 Hz.

On the scope I just monitored with statistics rms, ROV, FOV, Bwidth, Freq.
Didn't really know what to pick, so I choose what I thought would make more sense.

PO100
vs
X8

More or less performing the same, the PO100 has a base voltage 60mV higher.

At 500 Hz the PO100 starts underperforming.
The rms is switching often between 1.87V and 1.88V and the Bwidth drops sometimes, notice the min. at 277.02ms.
The X8 is rock solid, just one reading at 1.82V.

At 1000 Hz they both perform quite well, with the X8 moving to a steady 1.82V.

At 12000 Hz they both are doing well but the PO100 is often switching between 1.85V and 1.86V.

At 17000 Hz the PO100 voltage goes down to 1.83V with a few moments at 1.82V.

The X8 was set with the Slow Roll-off filter.
I guess the drop at 17 kHz on the PO100 is the result of AKM's Super Slow Roll-off.

In general the X8 was more clean and I wouldn't have expected anything different considering the massive price delta.

 

[ManniX]

This morning the Aune X8 started again very troubled by the AC noise from the amp.
This is how it looks like:

I kept the R channel connected to the amp and all this mess is a an audible change of tone.
Hard to spot listening to music, would probably result in a bad feeling.

 

[Talisman]

Thanks for the flanker update, indeed the second champion tested seems competent however when these failing specimens happen I always wonder
"And if it happened to me? I wouldn't be able to notice"
so I'm a bit hesitant.
Also, while probably inaudible after 40, with the level of proficiency achieved by even the cheapest DACs, I really see no reason to settle for a DAC that comes preconfigured with a treble rolloff.
By now smsl C200 is found new at about 160 euros.
Perfection is cheap in this field, TO ME there is no point in settling now

 

[ManniX]

I'm starting to doubt the cable or the connection with the leads, cause the Aune X8 today even connected to the power strip directly is showing issues.
Should get some crocodile clamps today and I'll see if it works better or not.
Could also be this unit has some issues.

Also, while probably inaudible after 40, with the level of proficiency achieved by even the cheapest DACs, I really see no reason to settle for a DAC that comes preconfigured with a treble rolloff.

I'm almost 50 and I can hear it very well.
It's a massive roll-off, starts at 8 kHz and by the time it reaches what I can still hear, about 13 kHz, it's huge.
The corresponding filter on the ESS it's still flat at that frequency and starts to roll-off smoothly after 16 kHz.
It's linear frequency response for me and it's the same at every fs, unlike with the AKM

By now smsl C200 is found new at about 160 euros.

It's a good option, considering the price.
It does have filter, DPLL selection and an RCU.
Only lacks the 12V trigger ports.

 

[ManniX]

By now smsl C200 is found new at about 160 euros.

Where did you find it at this price?
I can only see it at 250€ here.

If you don't need the headphone output, the DO100 is a better choice.
It's at 239€ here.

 

[VintageFlanker]

Where did you find it at this price?

Amazon FR had it on sale for 148€ a few months back. You should check this thread:

(Europe) Master Deals Thread on Audio Product Sales

Hey EU Folks, This is an alternative version of @amirm original Master "deals" (massdrop, ebay, Amazon, etc.) Thread on Audio Product Sales ... But this time specifically focused on deals available for shipping to (most) EU countries. It turns out that I am already an active member on French...

www.audiosciencereview.com

 

[ManniX]

Amazon FR had it on sale for 148€ a few months back. You should check this thread:

Thanks, awesome thread I didn't knew it!
I only found a post in Feb about 187$.
But looking around now I only see 250€, wonder if there's an hidden spot...

Anyway I just bought one of those 2nd hand Topping D50s in the last post to play with
Very useful thread to spend even more money eheh

 

[VintageFlanker]

I only found a post in Feb about 187$

DAC / Amplificateur Casque - S.M.S.L Aoshida C200 (vendeur tiers) – Dealabs.com

www.dealabs.com

It was from November (175€) to January (148€). But it went down to 165€ for Prime members since.

 

[Talisman]

Where did you find it at this price?
I can only see it at 250€ here.

If you don't need the headphone output, the DO100 is a better choice.
It's at 239€ here.

On amazon Italy, right now it's back at 219 but it's very often on sale at 164.
I got a used version like new at 120.

 

[GuyLux]

Hello !
Where can I find drivers for windows 8 /32 ?
Annonced to be compatible from W7, I can't find nothing except drrivers for W10, actually 5.58
Thanks for any help

 

[Veri]

Hello !
Where can I find drivers for windows 8 /32 ?
Annonced to be compatible from W7, I can't find nothing except drrivers for W10, actually 5.58
Thanks for any help

Maybe try the Downloads tab here

SMSL PO100 Digital Interface USB-C to Coaxial / Optical XMOS 24bit 192kHz DoP64 Silver - Audiophonics

The SMSL PO100 is a high performance digital interface based on a XMOS chip. The input is USB-C and the output is Coaxial or Optical Toslink. It supports streams up to PCM 24bit 192kHz and DoP64.

www.audiophonics.fr

(SMSLUSBAudioDriverV5.30.exe)

But these drivers should work on current Windows. On Windows 7 or old/non-serviced Windows 8 this .exe will probably fail yes..

 

[Toku]

Hello !
Where can I find drivers for windows 8 /32 ?
Annonced to be compatible from W7, I can't find nothing except drrivers for W10, actually 5.58
Thanks for any help

I think that V.4.67 or V4.82 will be the final version of the USB driver that can be used with Windows 7, Windows 8/8.1.
Although it is no longer posted on the SMSL HP, my PC has V4.41 to V5.58.
But I can't upload it because the file format can't be treated as an attached file in ASR.

Luckily I found it on the Shenzhen Audio download page.
Pages 13 and 14 list some older SMSL product drivers. You can use V4.82 or any older version.

DOWNLOAD CENTER - LOWEST PRICE GUARANTEE – SHENZHENAUDIO

download.shenzhenaudio.com

DOWNLOAD CENTER - LOWEST PRICE GUARANTEE – SHENZHENAUDIO

download.shenzhenaudio.com

Make sure to download SMSL's product drivers.

 

[GuyLux]

Thanks Guys !

Success !
I 've tried under W8 (on test and developpment workstation)
_5.30 cannot install on W8...
_4.82 as @Toku suggested yesterday, install : OK
So, I've to install to my "Music Center", only two sources
A small laptop W8 (2Go Ram 1.6Ghz) , tuned for audio, running Jriver-30
_SSD 2To : CD's converted to Flac files (USB connected )
A tuner-Radio : FM + DAB+ Internet radios +USB key <4Go, output optical spdif to DAC
Then sources to SMSL SU-9, >Preamp>Amp>Speakers
Jriver-30 plays my music and I have to select in parameters the output driver .
I play Flac files from Laptop, connect USB-2 to Dac SMSL SU-9 ,using SMSL 5.00 drivers
When I tried to install 4.82 drivers, I had a conflict with previous 5.00 already installed

The END : I connected USB PO100Pro in place of dac, Spdif to DAC and Music was !!!
Under W8, same drivers 5.00 can drive SMSL SU-9 or SMSL PO100Pro
Thanks to All !

 

[Schlippwhip68]

Yep.

BTW, I just updated the FR graphs with sampling frequencies from 44.1 to 192kHz. 88.2kHz appears to be also usable:
View attachment 272321

Ok, that drop off is quite hard to swallow as most digital music on mainstream platforms is streamed at that standard quality and the price of this thing pretty much aims at the mainstream users, so why allow that to drop off so steeply on such a common platform, it seems to be a bullet in ones own foot! Apart from that for the size it could have been a handy back up dac…

 

[jwmitchell]

S.M.S.L PO100 AK - Measurements / Round 2
​

View attachment 271967

Hi folks,

This is an update over my previous measurements of the S.M.S.L PO100 family. I will focus precisely on the PO100 AK, which not only is an USB to S/PDIF converter (as are the PO100 and PO100 PRO) but also a budget DAC, that claims to perform excellent for its price point (89$ MSRP, but I saw it discounted at 75€ right now at Amazon FR). The unit I bought back in December (and returned since) showed kind of mixed bag results. Pure SINAD was very good for one channel, while the other appeared to be significantly worse and gave me inconsistent numbers, runs after runs. In addition, it was not particularly great either in some other tests, like Jitter or Frequency Response.

The manufacturer, represented here by @SMSL-Mandy finally reacted to my review and suggested that my unit could faulty: "we suspect that the PO100 AK may be defective - parts soldering caused by this test". @SMSL-Mandy offered to send me another sample for a second evaluation, which I accepted:

S.M.S.L PO100, PO100 PRO & PO100 AK - Measurements (Digital Interfaces & DAC)

Hi @VintageFlanker, Merci so much for the reviews. I'm considering an SMSL PO100 PRO to connect my PC to a pair of Genelec 8351B. What cable would you recommend to connect the SMSL to the XLR AES/EBU input of my speakers? If possible easy ones to order from France... (amazon, Thomann...). The...

www.audiosciencereview.com

I received it a few days ago. As far I can see, it seems to be a regular production sample, with the exact same packaging as the previous PO100 AK I owned... So let's assume that it is not a cherry-picked unit, even if it had been safer to buy another random one for sale on the market.

I will only talk about overall performance of the second VS first sample in this post, for any other information, just check the original review:

S.M.S.L PO100, PO100 PRO & PO100 AK - Measurements (Digital Interfaces & DAC)

S.M.S.L PO100, PO100 PRO & PO100 AK Measurements Hey folks, It is time for my very last review of the year. A very special one, as there are three products to be measured today ! S.M.S.L released earlier this year the PO100, a tiny and fairly cheap USB to S/PDIF interface. Later in 2022...

www.audiosciencereview.com

Measurements​

Disclaimer: Measurements you are about to see are not intended to be as precise or extensive than what you get from a 30k€ AP. There is obviously both hardware and software limitations here, so not quite apples to apples comparison with Amir's testing. Still, this data is enough to have a pretty good idea if the gear is bad or not, stellar, broken, or sub-par...

- Instruments : E1DA Cosmos ADC (Grade B). RME ADI-2/4 PRO SE. E1DA Cosmos APU 60dB preamp is used for DR measurements. Output voltage is measured separately, using a DMM with a 0dBFS 1kHz tone.
- Software : REW V5.20.14, Multitone Loopback Analyzer 1.0.75 and RMAA 6.4.5 PRO,
- Method : 8 runs for each test, then I choose the closest to the average. Bandwidth and sampling rate to be specified for each test.
- S.M.S.L PO100 AK is running at full output (2.1V).

Note: Both my measurements process and graph presentation evolved a bit since the original review a couple of months ago. Anyhow, to give a fair apples to apples comparison, I used the exact same instrumentation and settings for the comparison charts below. I will then provide more extensive measurements, now made possible with my new equipment.​

Summary​

Tests​	1rst Sample​	2nd Sample​
Frequency response (from 40 Hz to 15 kHz)	+0.04, -1.28dB​	+0.02, -1.27dB​
Noise level (RMAA)	-117.0dB​	-119.1dB​
Dynamic range, dB (RMAA)	116.9dBA​	119.0dBA​
THD (REW)​	0.00024%​	0.00009%​
THD+N (REW)​	110.7dB​	115.8dB​
IMD + Noise (RMAA)​	0.00078%​	0.00042%​
Stereo crosstalk (RMAA)​	-102.1dB​	-119.4dB​
IMD at 10kHz (RMAA)​	0.00048%​	0.00039%​

Note: For the two samples, these numbers are the average of both channels. As such, Right channel (the faulty one) is obviously degrading the overall score of the first sample.

As a reminder, this is the original THD+N (SINAD) graph I posted, that clearly shows the disparity between both channels:
​

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz​

View attachment 271979​

And this is what I now get out of the second sample:

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz​

View attachment 271982

These are good news! Results are right on par with manufacturer's specs (-116dB THD+N), not to mention with excellent consistency regarding Noise and Distortion between Left and Right channels. Also, it is remarkably good for some 89$, USB powered unbalanced DAC. In fact, actually better than the venerable and pricier Topping D10S. Just for peace of mind, I double-checked it with my ADI-2/4 PRO SE:​

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz​

View attachment 271988

I use the digital trim of RME, to get closer to 0dBFS in REW RTA. Apart from absolute level, both results are consistent enough.

For comparison, @SMSL-Mandy published this SINAD FFT, done with an AP:

View attachment 271989

This is about 1.5dB better than my results, but I wondered if this could be A-Weighted. It appears to be the case, when looking at parameters.

Now, let's go deeper in the performance analysis...

Frequency Response was kind of an issue with the first sample. Still is. The PO100 AK uses Slow Roll-Off filter from its AK4493 chip, and it doesn't allow choosing another one... Which is very unfortunate when you have such an aggressive highs roll-off, running regular 44.1kHz sample rate. On the other hand, I am please to see almost identical voltage and amplitude for both channel (rare for budget DACs).
​

Frequency Response - 24b/44.1kHz​

View attachment 271992

Beware: Manufacturer's explanations for this could drive some of you mad...


In addition, they shared this FR capture:​

View attachment 271995
​

Well, I was effectively able to reproduce the exact same FR, but only with 88.2kHz sampling rates and above (separated FR, but amplitude is the same):​

Frequency Response - 24b/192/96/88.2/48/44.1kHz
View attachment 272317

​

Let's see the rest of benchmarks, with updated process (REW replacing RMAA, which remains for Crosstalk):​

Noise Level - 24b/44.1kHz
View attachment 272003


Dynamic Range - 24b/44.1kHz
View attachment 272004


Intermodulation Distortion SMPTE - 24b/44.1kHz
View attachment 272005


Intermodulation Distortion SMPTE Versus Level - 24b/44.1kHz
View attachment 272006


THD Versus Frequency - 24b/48kHz
View attachment 272020
​

A new test that was lacking in my previous reviews. The PO100 AK shows near-ideal consistency within audible range.​

Jitter - 24b/48kHz
View attachment 272007
​

This one is now a lot better than previous results: While Left was a touch better than Right, it was not "great" either. Now, we got the cohesive results out of both channels.​

Multitone 32 - 24b/192kHz
View attachment 272008​

Multitone gave me the same TD+N of -106.3dB I got out of the first sample's Left channel... Expect that Right is now "fixed".

​

Stereo Crosstalk - 24b/44.1kHz
View attachment 272026
​

Again, quite a bit better than it was before.

That is all. I am done...

​

Conclusions​

I will be short. Overall, PO100 AK truly showed an excellent performance for the class. It virtually nailed all tests, apart from Frequency Response. Perhaps, some of you could help me to speculate about present versus previous results, because I still have no clue about what went wrong with the first unit. Symptoms looked presumably like a ground loop issue, but I found quite uncommon to observe it in one channel only (I noticed that @amirm had one case recently, tho). Now that I may compare both my new and previous data in details, it is clear that bad performance of the Right channel indeed bled into Left's one in some tests, such as Crosstalk and Jitter. With this properly working sample, we just have very consistent behaviour for both, and I am surprised to observe such a good implementation of the AK4493 DAC chip... particularly at that price.

I would like to address my sincere thanks to @SMSL-Mandy for reacting to my review, sharing their own data and for sending another product. For now, I assume (say, I hope) that we could exclude the hypothesis of a cherry-picked SMSL PO100 AK...

So... are we good now, S.M.S.L? Not quite. The Frequency Response is still barely acceptable for my standards. It is fine to have this AKM Slow Roll-Off filter, but not when it remains the only one available. Since the PO100 AK does have no physical switch, I am sure that this still could be upgraded by firmware. At least, give your customer the choice of getting what any DAC is supposed to achieve: a flat Frequency Response from 20Hz to 20kHz. Just basics.

Flanker rating: Competent​

Thanks!

 

[Dumdum]

Just to confirm the original measurements of the second sample werent a golden sample... this is my AK measured with an E1DA... i found my olimex filter made a positive difference to the measurements from my lenovo x13 yoga

Excellent left to right matching