• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

SMSL SU-9 Balanced DAC Review


Staff Member
CFO (Chief Fun Officer)
Feb 13, 2016
Seattle Area
This is a review and detailed measurements of the brand new SMSL SU-9 Balanced USB DAC. It was kindly sent to me by one of their distributors, Shenzhenaudio. The SU-9 will be released September 30th and will cost US $439.99.

The SU-9 has a simpler but in my opinion more elegant look than previous SMSL DACs:

SMSL SU-9 Balanced USB DAC Audio Review.jpg

The display is now larger and courtesy of its fine resolution, nice to look at. The rotary control lets you navigate the menus by pressing and rotating. Alas, I could not figure out how to get out of the menus and had to wait for it to time out. Perhaps there is a way but not having read the manual, I did not know how. :) There is a remote of course which would make this simpler.

Back panel is what you expect in this class DAC plus addition of Bluetooth:

SMSL SU-9 Balanced USB DAC Back Panel XLR Toslink Coax inputs Audio Review.jpg

Power supply is included of course eliminating the external bricks that come with lower cost DACs. And of course balanced XLR output which I highly encourage for computer connected DACs.

DAC Audio Measurements
As usual, we start with our dashboard view:

SMSL SU-9 Balanced USB DAC Audio Measurements.png

Wow! Another DAC nearly maxing out the distortion+noise meter in my analyzer! The SINAD of 120 dB puts the SU-9 way up there in rankings:
Best USB Balanced DAC Review 2020.png

Zooming in:

Best balanced USB DAC in the world review 2020.png

Note that the SU-9 is capable of output above 4 volts which is nice. To show the performance at other output levels, I ran a sweep:

SMSL SU-9 Balanced USB DAC SINAD vs Output Level Audio Measurements.png

Since the SINAD measurement is noise limited (distortion alone is at 130 dB SINAD), having the output higher helps improve it as you see it in the above graph.

IMD distortion versus level shows excellent performance:

SMSL SU-9 Balanced USB DAC IMD Distortion versus level Audio Measurements.png

Our old friend the "ESS IMD Hump" is still there but 90% suppressed.

Linearity which is a measure of accuracy is perfect:

SMSL SU-9 Balanced USB DAC Linearity Audio Measurements.png

Jitter over USB is non-existent:
SMSL SU-9 Balanced USB DAC Jitter Audio Measurements.png

There is a digital PLL that helps reduce jitter but since there is none with USB input, it makes no difference. It however helps with Toslink jitter:
SMSL SU-9 Balanced USB DAC Toslink Jitter Audio Measurements.png

There may be a latency penalty though so if you are using Toslink for TV sound input, you may need to play with that. Fortunately the jitter that was there with default setting was not an audible concern anyway (at -120 dB and heavily masked by the signal itself).

Lots of filters are provided for any taste (imagined or otherwise):
SMSL SU-9 Balanced USB DAC Filter Audio Measurements.png

I like that there is a proper brickwall filter. I used that for the following test:

SMSL SU-9 Balanced USB DAC THD+N vs Frequency Audio Measurements.png

There is some frequency dependency here. I ran an FFT (not shown) and it showed that to be "imaging" components that were changing way up in frequency so not an audible issue.

Finally, multitone test showed how low the distortion is in SU-9 DAC:

SMSL SU-9 Balanced USB DAC Multitone Audio Measurements.png

EDIT: forgot to include the dynamic range in the original review:
SMSL SU-9 Balanced USB DAC  Dynamic Range Audio Measurements.png

And output impedance versus frequency:

SMSL SU-9 Balanced USB DAC Ouptut Impedance RCA Audio Measurements.png


SMSL SU-9 Balanced USB DAC Ouptut Impedance Audio Measurements.png

Be sure your amplifier has an input impedance above 3.7k Ohm (10 to 1 ratio) for XLR output and half and 1.3 k for RCA.

Looks like we started a trend to achieve perfection in desktop DACs and the SMSL SU-9 is yet another example of that. We have another great "instrument grade" DAC on our hands providing absolute transparency to the source beyond any threshold of human hearing. If you are hearing issues I suggest you either have your hearing examined, or learn to do a proper controlled test. Either way, what you hear is what is on your recording. Guaranteed!

It is my pleasure to highly recommend the SMSL SU-9. Great job.

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

I explained last night that I poked my palm last night trying to take the core out of Asian Pears in order to dry them. I swore I would not do any more but then I tasted the results this morning. Ah, they were fantastic! Sweet, full of pear flavor and all fit in a nice jar taking a fraction of space to store. So I dragged the bucket of pears out of the garage and prepared another batch to dry:

Pear Dehydrating.jpg

Despite filling 8 stacks I hardly made a dent in all the pears we have. And we have yet to pick the pears from two of trees!

Dehydrating uses electricity and while our rates are some of the lowest in the nation/world, it is not free. So appreciate some good sized donations to pay for it using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Last edited:
Wow, very fast ! Thank you !:)
Thanks for the review @amirm!
Knowing SMSL past records, especially with the M400, it would be interesting to have output impedance and frequency response measured for both RCA and XLR outputs.
But pears have obviously the highest priority. Thanks to you I want a slice of pear pie something like NOW!
Welp. Looks like I need to rethink my "it has to have 12v trigger in/out" requirement because this thing is absolutely killing it. I want it bad!
As an Englishmen's signature on this site indicates "Too many DACs> ".
So many dacs have not only about same measurements today; but also same features.
So how to choose, only by it's style or ... ?
As an Englishmen's signature on this site indicates "Too many DACs> ".
So many dacs have not only about same measurements today; but also same features.
So how to choose, only by it's style or ... ?
Feelings mostly
As an Englishmen's signature on this site indicates "Too many DACs> ".
So many dacs have not only about same measurements today; but also same features.
So how to choose, only by it's style or ... ?
Whats your source streaming, computer, AES, coax, toslink. Whats your amps input sensitivity Whats your budget
I found this tweet on Twitter from SMSL - posted yesterday.

smsl su9.JPG
Top Bottom