Measurements and Review of SOtM SMS-200 Network Player

[amirm]

This is a measurement and review of SOtM SMS-200 Networked Audio Player.

It retails for $450: http://www.sotm-audio.com/sotmwp/english/shop/sms-200/

If you are not familiar with this class of products, they sit on your network using a wired Ethernet connection and output using USB. Connect your favorite DAC to the USB port and then you can "talk" to it from any other networked computer or NAS with appropriate software.

In my case, I am running Roon on my music server elsewhere on the same Ethernet network. The SMS-200 like other devices like it, support a "Roon endpoint" meaning they show up as an audio device much like a hardwired USB DAC would be seen on your server.

The benefit here is that you can put your server anywhere on your home computer and just have this fanless little device in your audio system. In that sense, you don't have to build a fanless server. There are also NAS storage devices that support Roon and you could run the "Roon COre" on them just the same and address this device for DAC output/connection.

I will do a teardown in a later article but for now, these are intelligent little computers, running Linux and the necessary software stack for Roon, DLNA, etc.

While some people buy these devices for this remoting capability, quite a few also believe these devices produce better sound. The idea being that the device is small, "quiet" and hence, presents less opportunity to pollute the output of the DAC as a computer would. Well, the purpose of this evaluation is to see if this true.

For this testing, I used an iFi iDAC2 which retails for $349 to be driven first direct over USB from my laptop, and then through SMS-200. The test signal is the usual J-test which is at 12 Khz. Anything other than that one spike is noise/distortion. Here are the results using the stock power supply that comes with SMS-200:

Ignoring what is on the left for now, we see a response that is indistinguishable from direct USB connection. So no improvement in jitter or noise (of which there was so little in the iFi output anyway).

On the left though we see our friend, the switchmode power supply AC leakage. Due to EMI considerations, these low cost wall-wart adapters feed the output to their input in order to shunt high frequencies, while the same connection allows some of the mains current to bleed forward from AC line to their DC output. This in turn goes right through the DAC and shows up in measurements as increased mains/mains harmonics. We saw the same thing in the review of UpTone Regen (see http://www.audiosciencereview.com/f...eview-and-measurements.1829/page-6#post-46377).

So in that sense, this device adds noise/distortion as sold, not reduce it. The added noise is well below threshold of audibility but is of interest from engineering excellence and debunking the myth that these devices are cleaner than the PC. My laptop which generated the yellow line (using its own switchmode power supply no less) produces a more transparent result.

Fortunately our kind member anticipated this and also sent me a Vinnie Rossi Mini DC "ultracap" bank switching supply: http://www.vinnierossi.com/mini/

Love that old school, TO-3 transistor in the back. These are great from heat dissipation but expense so get little use these days. Brings back memories of building power supplies just like this back in 1960s-1970s when I first got into electronics.

Here is the outcome using the Vinni Rossi Mini Power Supply:

Now we are cooking with gas . The induced mains harmonics are gone as expected with this type of supply.

The power supply that comes with SMS-200 by the way, is a "Power-TEK" 9 volt at 1 amp. The Vinni outputs at 12 volts but because the SMS-200 has a switching dc-to-dc converter internally, it works just fine with variable/higher voltage.

So I decided to feed it other supplies. This time the iFi iPower power supply that came with the Sonore microRendu which I tested a while back: https://ifi-audio.com/portfolio-view/accessory-ipower/

Huston we have a problem! Not only does it have gobs of leakage current like the stock power supply, it also has higher frequency distortion spikes. Yuck. This sells for $49. I suggest staying with the stock supply instead of this option.

Finally, fresh from testing of the UpTone Iso Regen, I thought I give its switchmode power supply a chance here (made by MeanWell).

While there is still some mains contributions, the MeanWell is the best of the switchmode power supplies here! It has a grounded AC mains connection which allows the output high frequency shunt to go to that pin, rather than to hot/neutral. That reduces the amount of mains leakage contribution. And for $12, it is a bargain compared to the iFi.

I won't bore you with other supplies but I also tested by own linear supply which matched that of Vinnie Rossi Mini. I also tested with my Keysight U8001A which sadly showed some mains leakage (although better than all the switching supplies above).

Functionality
The SOtM SMS-200 is truly plug-and play. During my testing, I reconnected it dozens of times and Roon almost always rediscovered it. There is no software to install and everything just works. Boot up time is a bit slow (in order of a minute) but I assume most people will leave it always plugged in.

Summary
I plan to do some listening tests but for now, the measurements show that with the stock switchmode power supply, the SOtM SMS-200 causes a slight reduction in DAC performance due to mains AC leakage. Replacing its stock power supply with Vinnie Rossi solves that problem, bringing it to transparency.

On functionality front the device works excellently with Roon. It is a joy to just plug in a DAC and have it show up as a new device in Roon and be ready to go.

At $450, it is pricey option though.

On measured performance, I see no reason to acquire this to have better sound compared to a computer driving your DAC. Both the architecture of the device and my measurements confirm the same.

As always, I welcome comments, corrections, feedback, abuse of any kind, etc.

EDIT: see this thread for hardware teardown and review: http://www.audiosciencereview.com/f...o-player-hardware-teardown-and-pictures.1855/

 

[amirm]

FYI in follow on parts, I will compare this to Sonore microRendu and do a hardware teardown.

And much thanks for the member who loaned this device to me and has been patiently waiting for me to measure it.

 

[March Audio]

Want to try a Raspberry Pi with Roon? I can send one through.

 

[Thomas savage]

Have we measured a few linear psu ? Would be nice to find a few cheap ones that perform in a ideal way.

 

[amirm]

We can evaluate them but the question would be to what end? Even with linear power supply, these devices are not able to better the DAC performance.

The only exception would be the Schiit Modi 2 DAC and the best solution as we all know is to get a different DAC.

 

[amirm]

Oh wait . If you mean to improve the performance of these streamers, then yes, there may be merit there. But the mains noise I have identified so far is not audible.

 

[Thomas savage]

Oh wait . If you mean to improve the performance of these streamers, then yes, there may be merit there. But the mains noise I have identified so far is not audible.

I mean from a POV of wanting the best performance from products that come with unknown cheap SMPS.

Audible or not now you have shown a trend that cheap wall mounted SMPS inject mains harmonics , people will want to avoid them.

I know I will now most likely not want to use the one that came with my arcam IDAC for example, I'm now insecure about them if you like as will most audiophiles after reading this.

Testing A few cheap but well engineered alternatives would be great.

If we are not concerned with anomalies beyond audible thresholds then , honesty why even bother testing anything as it's all often beyond audible thresholds.

We either want to have the 'best' performance or we don't and audiophiles are audiophiles because they do and what's more they spend shit loads because they 'worry' about things like cheap SMPS.( I'd actually got passed that concern and made peace with the cheap one that came with my arcam but you messed that peace up!)

Now we can't all measure everything to find out 'if' there is a issue , going on the evidence here I'd rather buy a inexpensive linear psu and air on the side of caution but I don't want a crap one or a unnecessarily expensive one.

I want the best engineered performance from stuff that comes with cheap SMPS but I don't want to spend £1000 on a linear psu.

 

[Thomas savage]

We seem to be inconsistent at ARS in the regard of performance..,

one minute something is bad because it has a non ideal engineered performance ( below audible threshold but we kinda gloss over that) we make a big song and dance about injected noise etc .

The next minute on another product or technology ( like here) we are saying such injected noise is fine as it's all below the audible threshold.

This makes us look bad, it makes us look like we have some kind of agenda. It's called spin, people are sensitive to spin as it's what the media does and indeed what politicians do every time they open their mouths.

If a psu injects noise that can be easily avoided at a little extra cost then I want to avoid it, simple as that. No ifs no buts.

Of course if a dac has been designed to be used with a cheap SMPS and they have protected the outputs of the dac from being effected then that's great but that's hard to know unless you test every one of them , so what's left in the mind is doubt.

 

[Blumlein 88]

We seem to be inconsistent at ARS in the regard of performance..,

one minute something is bad because it has a non ideal engineered performance ( below audible threshold but we kinda gloss over that) we make a big song and dance about injected noise etc .

The next minute on another product or technology ( like here) we are saying such injected noise is fine as it's all below the audible threshold.

This makes us look bad, it makes us look like we have some kind of agenda. It's called spin, people are sensitive to spin as it's what the media does and indeed what politicians do every time they open their mouths.

If a psu injects noise than can be easily avoided at a little extra cost then I want to avoid it, simple as that. No ifs no buts.

Of course if a dac has been designed to be used with a cheap SMPS and they have protected the outputs of the dac from being effected then that's great but that's hard to know unless you test every one of them , so what's left in the mind is doubt.

Maybe audibility should be emphasized more.

OTOH, if an extra cost accessory, does nothing positive, or something inaudibly negative it simply is distasteful to me and should be pointed out. It won't corrupt the sound, but why would you not point out to others there is no point in using it or having it in a system.

If on the other hand, a lower cost item has inaudible noise vs a better item, then sure point it out with little reason to make a big deal out of it.

I don't see any inconsistency there. The only ones who do are those whose ox has been gored.

 

[Thomas savage]

Maybe audibility should be emphasized more.

OTOH, if an extra cost accessory, does nothing positive, or something inaudibly negative it simply is distasteful to me and should be pointed out. It won't corrupt the sound, but why would you not point out to others there is no point in using it or having it in a system.

If on the other hand, a lower cost item has inaudible noise vs a better item, then sure point it out with little reason to make a big deal out of it.

I don't see any inconsistency there. The only ones who do are those whose ox has been gored.

Oh I agree, if a product fails in all reasonable measure to provide the stated audible benefit then that's distasteful to me as well.

However leaving those kind of products behind we do strive for the 'best' engineered performance, than means if there's noise injected that can be easily mitigated we should promote awareness of that with a caveat that it's a 'ideal' performance we are gaining and may well not be audible.

Amir is always waxing on ( ) about good house keeping , best practice etc much of which has negligible audible effect.

I want good house keeping in my system, I want to keep noise as low as possible and minimise the risk of noise regardless of audibility. That's excellence in my mind, but measurable noise benefits not Swedish ground boxes etc

So I'd like to see tests of psu's and id like to know the best cheap SMPS and the best cheap linear psu.

I see a bit of a perceived inconsistency and my OX has a unperforated Hyde

 

[Soniclife]

Want to try a Raspberry Pi with Roon? I can send one through.

I'd like to see this done too, they can be roon endpoints so have the same functionality as this, be interesting to see if it's better, same or worse than the much more expensive options. The basic functionality of allowing your music server to be outside of your listening room is desirable to many.

 

[Johnseye]

I mean from a POV of wanting the best performance from products that come with unknown cheap SMPS.

Audible or not now you have shown a trend that cheap wall mounted SMPS inject mains harmonics , people will want to avoid them.

I know I will now most likely not want to use the one that came with my arcam IDAC for example, I'm now insecure about them if you like as will most audiophiles after reading this.

Testing A few cheap but well engineered alternatives would be great.

If we are not concerned with anomalies beyond audible thresholds then , honesty why even bother testing anything as it's all often beyond audible thresholds.

We either want to have the 'best' performance or we don't and audiophiles are audiophiles because they do and what's more they spend shit loads because they 'worry' about things like cheap SMPS.( I'd actually got passed that concern and made peace with the cheap one that came with my arcam but you messed that peace up!)

Now we can't all measure everything to find out 'if' there is a issue , going on the evidence here I'd rather buy a inexpensive linear psu and air on the side of caution but I don't want a crap one or a unnecessarily expensive one.

I want the best engineered performance from stuff that comes with cheap SMPS but I don't want to spend £1000 on a linear psu.

First of all, I don't think we should be sizing up a device by whatever PSU is used with it. Many devices come without one, or offer a cheap one because the manufacturer knows you're going to replace it with something better. Stick with one high quality, low noise PSU and use that to test devices so the noise from the PSU isn't a factor in determining whether it's a quality product or not.

The fact that different PSUs will add noise isn't new news and many audiophiles already know this. Maybe even 99% of them. There is a decent market for aftermarket LPSUs for this reason. If you don't want to buy an after market LPSU then you can invest more in better quality "stuff" that builds in better quality PSUs. That doesn't discount SMPSs because some can be well made. Since Amir is reviewing the sMS-200 it would be interesting to get his take on the new sPS-500 SMPS. I can't say whether it's a good one or not because I know nothing about it except what I've read. My understanding is that it has a ripple of about 100mV, but the filtering on it makes it better than many PSUs out there.

I go back to this info time and again, because I trust the folks at Benchmark. They're very transparent. Have a read. Of course it's marketing but let me know what you think. There's also a decent video. And no, I don't work for Benchmark.

https://benchmarkmedia.com/blogs/ap...audio-myth-switching-power-supplies-are-noisy

THIS MYTH GOES SOMETHING LIKE THIS:

"Switching supplies are noisy."

"Linear power supplies are best for audio."

We disagree!

About 5 years ago, Benchmark stopped putting linear power supplies into our new products, and we replaced them with switching power supplies. We did this because linear supplies are too noisy. Yes, you read that correctly, linear supplies are noisy! A well-designed switching power supply can be much quieter than a linear supply.

LINEAR POWER SUPPLIES CAUSE HUM
The noise problem is due to the fact that linear power supplies have large transformers and other magnetic components that operate at the AC line frequency (50 Hz to 60 Hz). These line frequencies are audible, and we are all too familiar with the hum and buzz that audio products can produce. It is no secret that this noise is caused by the power supply, but few people understand why it can be so hard to eliminate. Most people think that hum is caused by conducted interference (AC ripple on the power supply rails), but this is rarely the case. Most AC hum is caused by magnetic interference, and this can be very hard to eliminate.

HUM IS USUALLY CAUSED BY MAGNETIC INTERFERENCE
Transformers are magnetic devices. Power is magnetically transmitted between a transformer's input and output windings. In a linear supply, power is transmitted from the AC line side of a transformer to the low-voltage secondary side using an AC line-frequency magnetic field. Unfortunately, transformers are never perfect, and some energy always escapes through stray magnetic fields. These stray fields can interfere with virtually every electrical conductor in an audio product. Magnetic shielding is expensive and it has limited effectiveness when sensitive circuits are located in close proximity to a strong field.

POWER AMPLIFIERS ARE THE WORST OFFENDERS
The power supplies in high power devices, such as audio power amplifiers, can emit very strong magnetic fields. These strong fields tend to limit the noise performance (SNR) of power amplifiers. These magnetic fields can also cause interference with audio products that happen to be too near the amplifier. Audio cables that enter, exit, or pass near the amplifier may also pick up unwanted hum and buzz. For this reason, it is usually very important to keep the power amplifier well separated from cables and other components in the audio system.

 

[amirm]

Since Amir is reviewing the sMS-200 it would be interesting to get his take on the new sPS-500 SMPS. I can't say whether it's a good one or not because I know nothing about it except what I've read. My understanding is that it has a ripple of about 100mV, but the filtering on it makes it better than many PSUs out there.

I looked up their spec page and it has no performance specifications. Or any design features. So I can't say anything about it unfortunately.

If someone wants to buy it, I will be happy to measure it . At $500 is a bit out of my budget right now.

 

[Fitzcaraldo215]

Computer Audio is still very much DIY-land for many, and they may enjoy the hobby partly for that reason. Some people just love audio in all its flavors because of the tweakability. I myself don't and I am no fan of products that do not come equipped and performance spec'ed as a complete finished component. That includes power supplies or whatever. They are not a separate component, in my view.

I avoid stuff like that and all the mythology associated with the power supply game plus all the anecdotal user testimonials of the wonders of certain power supplies. Power supplies may indeed make a difference sometimes, but count me out of experimenting with them. I'd rather spend my time listening to music. And, I would rather see manufacturers just equip their gear with the power supply that will make it perform at its best in the first place. That is their job.

In spite of the craziness and fanaticism, I still love many aspects of what Computer Audio can do. I find it possible to stay reasonably sane and rational with good products that sound great and perform well. I have been weak and backslid on that a few times, but I learned my lesson.

 

[Johnseye]

Computer Audio is still very much DIY-land for many, and they may enjoy the hobby partly for that reason. Some people just love audio in all its flavors because of the tweakability. I myself don't and I am no fan of products that do not come equipped and performance spec'ed as a complete finished component. That includes power supplies or whatever. They are not a separate component, in my view.

I avoid stuff like that and all the mythology associated with the power supply game plus all the anecdotal user testimonials of the wonders of certain power supplies. Power supplies may indeed make a difference sometimes, but count me out of experimenting with them. I'd rather spend my time listening to music. And, I would rather see manufacturers just equip their gear with the power supply that will make it perform at its best in the first place. That is their job.

In spite of the craziness and fanaticism, I still love many aspects of what Computer Audio can do. I find it possible to stay reasonably sane and rational with good products that sound great and perform well. I have been weak and backslid on that a few times, but I learned my lesson.

Some people like simplicity which have made companies like Apple so successful. Just give it to me, make sure it works and let me enjoy. Nothing wrong with that at all. There are many things in which I subscribe the same philosophy. Then you have the open source group where you can dive into the detail and tweak to your heart's content. There are times when I like to do that as well. Everyone has their own interests and some people like to learn more about things than others. There's nothing wrong with either approach, or even a combination of the two.

 

[amirm]

Finished the hardware teardown: http://www.audiosciencereview.com/f...o-player-hardware-teardown-and-pictures.1855/

 

[jtwrace]

Is it possible to measure the noise on the USB (mV) on the sMS-200?

I have an Allo https://allo.com/sparky/usbridge.html and they say:

How about RPI? RPIs are great and very energy efficient, but on USB they have 2 major flaws. First is that bandwidth is shared between the 2 USB ports (so in fact there is only one USB), and second is that ethernet is also shared on same bus! Of course, you also have the noise on USB at about 60mV.

Maybe Sparky? The 2 USB ports (next to the ethernet port) share one input to the CPU (split by a hub). Noise on USB bus is about 27mV (pretty good) and ethernet is completely apart (bus is not shared). So it's ok, but not great.

 

[Jinjuku]

I have a BeeLink Mini-PC coming with the Celeron N3450 Quad CPU / 4GB RAM / 64GB eMMC for $169. I believe they can take additional M.2 Sata storage. Comes with a SMPS but they only need 1.5A / 12VDC so this LPS would work for $30.

So for $200 you could turn this into USB streamer. Probably run with the SoTM with no one knowing the difference if you didn't tell them.

 

[jtwrace]

I have a BeeLink Mini-PC coming with the Celeron N3450 Quad CPU / 4GB RAM / 64GB eMMC for $169. I believe they can take additional M.2 Sata storage. Comes with a SMPS but they only need 1.5A / 12VDC so this LPS would work for $30.

I'm not quite sure what that's in reference to but thanks.

 

[Jinjuku]

I'm not quite sure what that's in reference to but thanks.

Since we are talking about USB Streamers.... Just click the links.