SMSL DO400 DAC & HP Amp Review

[amirm]

This is a review and detailed measurements of the SMSL DO400 DAC and balanced headphone amplifier. It was sent to me by Aoshida Audio and costs US$499.

It is not quite visible but there are contours on top of the front panel sheet metal, giving the DO400 a higher end look. I expected the user interface to be revamped as well but it is standard SMSL UI. It is easy to use though so not a practical issue.

Back panel shows the usual connections:

I wish there was trigger out support though. And some would like HDMI ARC instead of I^2S.

Instead of running my usual measurements, I omitted a few and added a bit of others.

For these measurements I decided to upgrade to the latest version of Audio Precision software which finally supports WASAPI audio instead of having to use ASIO emulation. Was so happy to see this. I connect to the SMSL and I am shocked to see lots of distortion. SINAD was a poor 95 dB! I hunt around, change things, read the manual over and over again and still can't figure out why there is so much distortion. Frustrated, I switched back to ASIO and same problem persisted!!! I then remembered the so called sound color setting. Look in there and it is set to "Rich1" instead of "standard!" Switched it to standard and everything was well. I hope SMSL changes the default to standard. As otherwise, you have paid a lot of money for a product that underperforms a dongle when it comes to distortion....

SMSL DO400 Measurements
I started with volume set to 0 dB and XLR output:

Distortion is incredibly low at -140 dB! Noise dominates SINAD as usual, and places DO400 easily in our top 20 DACs:

RCA output costs you a bit but not much:

Since I was on topic of sound color, I decided to measure the impact of various settings:

As you see, it costs fair bit in performance. Strangely, "tube" mode is the same as Rich 1, at least in total THD.

I dug in more into tube mode:

It does push second harmonic but nowhere near what a real tube product would do. I doubt very much typical person can hear its impact.

Back to noise, performance is superb:

Jitter is absolutely clean with USB:

As is Multitone:

I didn't check which filter was active for our wideband test:

Next, I measured balanced headphone out. I found it super clean in low gain mode with plenty of power:

As you can see, in high gain with 32 ohm, it really smokes! That should be plenty to drive any headphone to any loudness level.

There is no negative, low gain mode so in this department, the DO400 turns in middling score:

So very sensitive IEMs may not be a good fit.

Conclusions
SMSL turns in some of their best engineering in the DO400. DAC performance is state of the art. And headphone output is very clean in low gain mode and very powerful in high gain mode. We could use a couple of other features and a very low gain mode for IEMs. But that is it.

Price is reasonable for this class of product and I like the new front panel.

I am going to recommend the SMSL DO400.
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As always, questions, comments, recommendations, etc. are welcome.

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[RogerSmith]

Nice, like so many others from SMSL, hard to know what is different in all these models.

 

[Rja4000]

Thanks for the review.
Another nice product.

I wish there was trigger out support though. And some would like HDMI ARC instead of I^2S.

Me too !

 

[daniboun]

Teardown see attached pics

It looks like a replica of the LOXJIE D40 PRO

 

[Mathijs Kok]

Combine that with the tiny CD transport just featured, and you have a heck of a system for a good headphone.

 

[Rick63]

Well look at that, 16 of the top 20 highest measured SINAD DACs are either Topping or SMSL.

 

[Jas0_0]

Thanks Amir. Looks great, but still looking for a DAC other than RME with dynamic loudness

 

[ocinn]

Well look at that, 16 of the top 20 highest measured SINAD DACs are either Topping or SMSL.

*17, VMV is an SMSL sub-brand.

 

[amirm]

The two companies have been the earliest in the race so no wonder they are still on top. SMSL though, had been going sideways on a few products though. So good to see them back to their roots.

 

[RandomEar]

*17, VMV is an SMSL sub-brand.

Loxjie is an SMSL "sister brand" (same business group), as far as I know. So we could count it as 17.5

Apart from that: Excellent performance, as expected by now. But still that awful typography and weird color mix in the UI, which both look like they were done by a six year old.

Also, most of those "sound color" options are pretty dumb. If the worst case SINAD is still about on par with the best case an audio CD can deliver, then what's the point? I mean, other than marketing and making gullible people happy to "hear a difference" which isn't as audible...

 

[Roland68]

Nice, like so many others from SMSL, hard to know what is different in all these models.

Teardown see attached pics

It looks like a replica of the LOXJIE D40 PRO

In fact, this is quite simple to explain, as manufacturers often produce technically identical models—featuring different front panels, displays, enclosures, designs, and connectivity options—specifically for different distribution channels.
For instance, the Loxjie D40 Pro, Loxjie D60, and SMSL DL400 all utilize the same technical platform as the DO400 model tested here.

A comparison of the reviews for the DO400 and the Loxjie D40 Pro further reveals that even batches and models produced separately—yet sharing the same technical foundation—exhibit only an extremely negligible degree of variation.

 

[daniboun]

In fact, this is quite simple to explain, as manufacturers often produce technically identical models—featuring different front panels, displays, enclosures, designs, and connectivity options—specifically for different distribution channels.
For instance, the Loxjie D40 Pro, Loxjie D60, and SMSL DL400 all utilize the same technical platform as the DO400 model tested here.

A comparison of the reviews for the DO400 and the Loxjie D40 Pro further reveals that even batches and models produced separately—yet sharing the same technical foundation—exhibit only an extremely negligible degree of variation.

The fact is SMSL / Loxjie and many others are part of the same company (holding)

 

[welwynnick]

Thanks Amir. Great test, great product.

I completely agree about having HDMI eARC instead of I2S. (Never thought I'd hear myself say that!)

The best DACS are getting so good that it might be time to expand the vertical scale on the FFT from -160 to -170/-180 dB?

 

[Roland68]

The fact is SMSL / Loxjie and many others are part of the same company (holding)

And let's not forget Sabaj.

That is correct; however, SMSL also manufactures devices for other entities—such as Aoshida and Shenzhenaudio—in addition to their own line. Even if a device bears the SMSL branding, all matters regarding warranty coverage, support, firmware updates, and troubleshooting are handled exclusively through the respective distribution channel—not directly through SMSL itself—as many buyers on the forum have already discovered.

However, on the SMSL website, under the "Purchase Link" section, you can see which distributor is assigned to a specific device; for the DO400 model reviewed here, for instance, that distributor is Aoshida. Similarly, all the "RAW" series devices are assigned to Shenzhenaudio. This also explains why these particular devices are not available at retailers like HiFi-Express, where you won't find any "DO" or "RAW" series models.

There are a few other special features and dependencies among the different devices and companies, but that would be too off-topic for this thread.

My thanks also go to @amirm for this test; the DO400 has been at one of my workplaces for over 2 years and works very reliably.

 

[welwynnick]

For these measurements I decided to upgrade to the latest version of Audio Precision software which finally supports WASAPI audio instead of having to use ASIO emulation. Was so happy to see this. I connect to the SMSL and I am shocked to see lots of distortion. SINAD was a poor 95 dB! I hunt around, change things, read the manual over and over again and still can't figure out why there is so much distortion. Frustrated, I switched back to ASIO and same problem persisted!!! I then remembered the so called sound color setting. Look in there and it is set to "Rich1" instead of "standard!" Switched it to standard and everything was well. I hope SMSL changes the default to standard. As otherwise, you have paid a lot of money for a product that underperforms a dongle when it comes to distortion....

SMSL are probably doing what Topping and Okto do with some their products, and use the ESS THD Compensation function. This is intended to minimise the distortion of the completed product, but these manufacturers appear to be offering the user the ability to increase 2H & 3H distortion. I think it's to counter objectivist comments about products having distortion that is TOO LOW and sounds cold and analytical, and steer slightly towards the warm and cosy sound of tubes with much more 2nd harmonic in particular.

Topping offer a fairly extreme Valve Mode in their Sound Simulation Function:

 

[ObjectiveSubjectivist]

Cool, waiting for smsl to implement peq on their devices.

 

[CopperFox]

Would it be possible to have some sort of power vs frequency measurement for headphone amplifiers, like you have done for power amplifiers with the 40Hz measurement? Most of the power amplifiers measured here have had some low frequency deficit and I assume the same would be true for headphone amplifiers, with maybe some exceptions. Would be interesting to see which ones those exceptions are.

 

[daniboun]

And let's not forget Sabaj.

That is correct; however, SMSL also manufactures devices for other entities—such as Aoshida and Shenzhenaudio—in addition to their own line. Even if a device bears the SMSL branding, all matters regarding warranty coverage, support, firmware updates, and troubleshooting are handled exclusively through the respective distribution channel—not directly through SMSL itself—as many buyers on the forum have already discovered.

However, on the SMSL website, under the "Purchase Link" section, you can see which distributor is assigned to a specific device; for the DO400 model reviewed here, for instance, that distributor is Aoshida. Similarly, all the "RAW" series devices are assigned to Shenzhenaudio. This also explains why these particular devices are not available at retailers like HiFi-Express, where you won't find any "DO" or "RAW" series models.

There are a few other special features and dependencies among the different devices and companies, but that would be too off-topic for this thread.

My thanks also go to @amirm for this test; the DO400 has been at one of my workplaces for over 2 years and works very reliably.

BTW : you can get any Aoshida devices directly from their site :

AOSHIDA AUDIO

Aoshida-audio is one of leading Platforms which specializing in providing Audio Products, such as: Amplifier, Decoder, Player, Headphone,Cable and Accessories with high quality etc. Aoshida-audio will unswervingly continue focusing on more excellent servi

aoshida-audio.com

 

[Dk33145]

Cool, waiting for smsl to implement peq on their devices.

1000% this. Not sure who at SMSL approved spending R&D $$$ on fake tube modes over a standard feature like peq. Middling SNR performance on the amp section too.

 

[respice finem]

A "coloured" factory default setting is a no-go for me. Probably many won't know.
Hope such "brilliant ideas" will not spread.
And no PEQ...