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SMSL DO300 DAC Review

Rate this stereo DAC:

  • 1. Poor (headless panther)

    Votes: 6 2.5%
  • 2. Not terrible (postman panther)

    Votes: 9 3.8%
  • 3. Fine (happy panther)

    Votes: 49 20.8%
  • 4. Great (golfing panther)

    Votes: 172 72.9%

  • Total voters
    236

amirm

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This is a review and detailed measurements of the SMSL DO300 balanced stereo USB DAC with Bluetooth. It was sent to me by the company and costs US $549 although I see it on sale for $490.
SMSL DO300 Stereo USB DAC Balanced Review.jpg

The DO300 naturally follows the design language of other recent SMSL products. I like the colorful display and largish displayed volume level. Back panel doesn't provide any surprises:
SMSL DO300 Stereo USB DAC Balanced Remote Control Back Panel Review.jpg

A minor nit: I like to see color codec RCA jacks with red indicating right channel. Looking from above, it is hard to know which channel is which. I like to see trigger support to sequence powering on downstream products as well.

SMSL DO300 DAC Measurements
As usual, let's start with our usual dashboard and XLR Output with volume set to default 0 dB (it goes up to 2 dB):
SMSL DO300 Stereo USB DAC Balanced Measurements.png

You would think I would get used to such high SINAD (sum of noise and distortion) in products from SMSL but I still get a pleasant surprise when I see numbers north of 123 dB! This naturally lands in our (rather silly) top 20 best DACs ever tested rankings:
best USB stereo dac review 2023.png


RCA output shows the typical reduction in SINAD but still fully transparent:
SMSL DO300 Stereo USB DAC RCA Measurements.png


Volume control is dead on accurate so -30 dB is indeed, that level in output. Using that, I measured the effect of volume control on output SINAD:
SMSL DO300 Stereo USB DAC Balanced SINAD vs Volume Measurements.png

The glitches are instrumentation issues. Response naturally scales with output voltage.

IMD test shows no sign of "hump" despite use of ESS DAC:
SMSL DO300 Stereo USB DAC Balanced IMD Measurements.png


Multitone performance is exceptional of course:
SMSL DO300 Stereo USB DAC Balanced Multitone Measurements.png


As is noise performance:
SMSL DO300 Stereo USB DAC dynamic range Measurements.png


Linearity is perfect as we would expect:
SMSL DO300 Stereo USB DAC Balanced Linearity Measurements.png


Jitter is perfect over USB and essentially the same over Toslink:
SMSL DO300 Stereo USB DAC Balanced Jitter Measurements.png


We have our usual suite of filters including "off:"
SMSL DO300 Stereo USB DAC Balanced Filter Measurements.png

SMSL DO300 Stereo USB DAC Balanced Filter Frequency Response Measurements.png


I would personally use Fast Linear and be done with it. Note that "off" causes a large rise in output level so be careful when comparing that to other settings:
SMSL DO300 Stereo USB DAC Balanced Filter Frequency Response Off Measurements.png


It also has that screwed up frequency response so best left unused.

The excellent filter response translates to superb THD+N versus frequency:
SMSL DO300 Stereo USB DAC Balanced THD+N vs Frequency Measurements.png


Conclusions
What can I say other than the DO300 being extremely well executed as we expect from SMSL. Yes, company produces many such DACs. It is not my job to sort through them. It is yours! :)

I am happy to put SMSL DO300 DAC on my recommended list.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
Volume control is dead on accurate so -30 dB is indeed, that level in output. Using that, I measured the effect of volume control on output SINAD:
SMSL DO300 Stereo USB DAC Balanced SINAD vs Volume Measurements.png


The glitches are instrumentation issues. Response naturally scales with output voltage.
Thanks for the measurements !

What exactly does mean this plot ?
Measuring result with volume control is interesting but I'm not sure how to read it.
 
What exactly does mean this plot ?
Measuring result with volume control is interesting but I'm not sure how to read it.
It more of a curiosity as what it shows can be guessed. The reason for it is that normally tests are performed with volume is set to 0 dB/Max. In use, you would be using the volume control set to lower value otherwise your amp will be at max loudness. Folks wanted to see the impact of lowering the volume on SINAD. So that is what I am measuring. Predictably, SINAD which is dominated by noise (since distortion is so low) scales with output voltage. The lower the volume, the more noise shows up.

Interpreting the results, it says that if you set the volume to -30 dB, you still have SINAD of 100. As long as that is max playback level, you should have silence.
 
This "filter off" setting looks kind of "experimental", forgotten to delete from the firmware before release?
I imagine it is either feature of the ESS DAC chip used or is kludged somehow to go into that mode. Someone less lazy than me needs to dig into the datasheet assuming it is public. :)
 
The AES/EBU interconnect on the back panel is a surprising attack. Vote #4

A minor nit: I like to see color codec RCA jacks with red indicating right channel. Looking from above, it is hard to know which channel is which. I like to see trigger support to sequence powering on downstream products as well.
The colored Red-White RCA jacks are old components. This one, not-colored, is modern. Probably better component because mostly found on new device.

All these RCAs are not colored:
View attachment 278756
 
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It more of a curiosity as what it shows can be guessed. The reason for it is that normally tests are performed with volume is set to 0 dB/Max. In use, you would be using the volume control set to lower value otherwise your amp will be at max loudness. Folks wanted to see the impact of lowering the volume on SINAD. So that is what I am measuring. Predictably, SINAD which is dominated by noise (since distortion is so low) scales with output voltage. The lower the volume, the more noise shows up.

Interpreting the results, it says that if you set the volume to -30 dB, you still have SINAD of 100. As long as that is max playback level, you should have silence.
That could be interesting if you have a relay/stepped attenuator, as an example, instead of a digital volume control.

I find the X axis confusing though.
Couldn't you scale it on dBr vs 0dB attenuation voltage ?

Ok, it's interesting anyway.
I suppose the jump in SINAD is due to the AP switching range ?
 
I like to see trigger support to sequence powering on downstream products as well.
I really appreciate the attention to this. If it is too much of a hassle to power on or off a stack of components, the rest of my household is just not going to bother and use TV speakers or their phone. If someone fires up Spotify Connect, everything should respond and it should work as expected.
 
I imagine it is either feature of the ESS DAC chip used or is kludged somehow to go into that mode. Someone less lazy than me needs to dig into the datasheet assuming it is public. :)
"The ES9039MPRO & ES9039PRO has 7 pre-programmed digital filters." according to the datasheet, and no Off or Super Slow filter, so the 8th Off filter is an SMSL filter or simply no digital filter.
 
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SMSL releases too many DACs.

What is the actual difference between a DO300 and a SU-9 PRO ?
Same chip used, same performances, almost the same connectivity, almost the same look, and alsmost the same price on Audiophonics.

Why choose one instead of the other ?
 
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I could swear Amir has measured the exact same SMSL DAC a few months ago. No innovation, as usual.

They should move on to other things ...
 
The marketing strategy of this company is a real dilemma. Why make 10 DACs in the range 150-1.500$? it just creates confusion in the clients head.
 
I find the X axis confusing though.
Couldn't you scale it on dBr vs 0dB attenuation voltage ?
I have no choice there unfortunately. There is no direct support for this type of testing in AP software. I kludge it by having a running measurement so the x axis is always time. For this reason, I added the second line which is dashed red. It shows the voltage output. I can make it dB but I thought members wanted it in voltage as to match it to their amplifiers.
 
This "release policy" might have something to do with "certain realities" on the components market IMHO. You can only build with parts you can get.
 
What's happend @amirm? Cannot sleep these days so you test and publish like never?
:) No, just getting hit with deadlines after deadlines. This one has been sitting here for three months so I needed to get it out. But yes, I did have a big cup of coke full of caffeine.... :)
 
:) No, just getting hit with deadlines after deadlines. This one has been sitting here for three months so I needed to get it out. But yes, I did have a big cup of coke full of caffeine.... :)
Or do it the medical way: just declare the deadlines as dead :p (just kidding of course)
 
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