SMSL SU-9 Balanced DAC Review

[Kisch]

This DAC looks very interesting to me. Just curious how is output volume regulated when in preamp mode? By volume knob, yes I know. But I mean how does it solved technically.

 

[AnalogSteph]

This DAC looks very interesting to me. Just curious how is output volume regulated when in preamp mode? By volume knob, yes I know. But I mean how does it solved technically.

Digital attenuation at 32 bit (int or float) resolution, most likely. At >126 dB(A), measured dynamic range is so high that you can afford doing this... output noise level by itself is <2.5 µV(A) (<-115 dBV(A)), that's lower than for many analog preamps. You couldn't keep distortion levels as low as they are any other way - even a PGA2320 would be a bottleneck, not to mention drive up the BOM cost.

In any playback setup that requires 0 dBu to +16 dBu of input for 110 dB SPL out at listening position, this DAC should serve you very well as a preamp... possibly even at -4 dBu still. If you need neither the DSP features and even lower noise floor of an RME ADI-2 DAC FS nor the +24 dBu (+27.5 dBu) studio level output of a Benchmark DAC3, there is little reason to spend any more. The DAC portion by itself is essentially about as good as it gets.

 

[Kisch]

Digital attenuation at 32 bit (int or float) resolution, most likely. At >126 dB(A), measured dynamic range is so high that you can afford doing this... output noise level by itself is <2.5 µV(A) (<-115 dBV(A)), that's lower than for many analog preamps. You couldn't keep distortion levels as low as they are any other way - even a PGA2320 would be a bottleneck, not to mention drive up the BOM cost.

In any playback setup that requires 0 dBu to +16 dBu of input for 110 dB SPL out at listening position, this DAC should serve you very well as a preamp... possibly even at -4 dBu still. If you need neither the DSP features and even lower noise floor of an RME ADI-2 DAC FS nor the +24 dBu (+27.5 dBu) studio level output of a Benchmark DAC3, there is little reason to spend any more. The DAC portion by itself is essentially about as good as it gets.

Thank you for reply. It seems I was frozen in times, when digital volume control had significant negative impact to SQ. I have Dynaudio BM5mk3 and my plan is to connect it directly to SU9 RCA or XLR and set volume from SU9. Dynos sit quite close to me on my working desk so I play mostly at low levels.

 

[kgs51]

I will be using dual xlr cable(female) on my DAC to dual rca cables on my powered speaker. Is this a better connection then if I did dual RCA cables from the DAC to dual RCA cables on my speaker.

 

[Veri]

I will be using dual xlr cable(female) on my DAC to dual rca cables on my powered speaker. Is this a better connection then if I did dual RCA cables from the DAC to dual RCA cables on my speaker.

No, serves absolute no point doing this. Connection is still RCA, unbalanced.

 

[kgs51]

Thanks.

 

[zoqui]

No entiendo por qué conectado a la PC, el dac muestra la frecuencia de muestreo y si lo conecta a Android a través de USB, siempre muestra 48 khz, incluso si es otro.

 

[Moderate Dionysianism]

No entiendo por qué conectado a la PC, el dac muestra la frecuencia de muestreo y si lo conecta a Android a través de USB, siempre muestra 48 khz, incluso si es otro.

Android ejecuta upsampling de audio para 48khz por predefinicón, así funciona el mixer interno del sistema. Para enviar el señal 'original' para el DAC se necesita de una app que circunvale el interface audio de Android (semejante al modo ecxlusivo en Windows) - por ejemplo USB Audio Player Pro, Neutron Player o HiBy Music.

 

[DougNoOnions]

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:

View attachment 84224

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:

View attachment 84225

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:

View attachment 84226

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:
View attachment 84227

Zooming in:

View attachment 84228

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:

View attachment 84229

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:

View attachment 84230

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

Linearity which is a measure of accuracy is perfect:

View attachment 84231

Jitter over USB is non-existent:
View attachment 84232

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:
View attachment 84233

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):
View attachment 84235

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

View attachment 84236

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:

View attachment 84237

EDIT: forgot to include the dynamic range in the original review:
View attachment 84556

And output impedance versus frequency:
RCA:

View attachment 84558

XLR:

View attachment 84559
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.

Conclusions
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:

View attachment 84239

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/

Thanks for the review, I just bought based in your analysis

 

[Kisch]

So Su-9 arrived and it is sitting on my desk. In my office. Now I enjoy my work a lot more.

 

[Moderate Dionysianism]

Now I enjoy my work a lot more

So you're saying that your work as a pro World of Tanks player got even more enjoyable? Goes to show there's nothing a healthy dose of SINAD can't improve

 

[Kisch]

So you're saying that your work as a pro World of Tanks player got even more enjoyable? Goes to show there's nothing a healthy dose of SINAD can't improve

Ha ha, no it is just twitch and my favourite streamer. My main job is in IT department.

 

[_Piotr]

Posting this, so You won't do the same mistake I did.
I've set the brightness to 0, and now I have no way of changing it back

 

[ninetylol]

Posting this, so You won't do the same mistake I did.
I've set the brightness to 0, and now I have no way of changing it back

View attachment 114119

You can probably still See it in a dark room.

 

[_Piotr]

Managed to get it back by doing a blind loop of ok => up => ok => up => exit
Its is a 9th position in the menu, but it remembers your last menu position and I didn't.

 

[Kisch]

Managed to get it back by doing a blind loop of ok => up => ok => up => exit
Its is a 9th position in the menu, but it remembers your last menu position and I didn't.

Nice! Interesting thing is my SU-9 display still lit even set to 0.

 

[BattleScarze]

Does anyone know if the display can be turned off?

 

[cursive]

Does anyone know if the display can be turned off?

Well, like _Piotr just said you can turn the brightness down to zero in the menu so the display is totally off, but this isn't advised as then you can't tell where you're at on the menu, and can't see what options you're choosing.

To me it's not a big deal to have the screen on all the time, even in a dark room on low brightness it's very dim, and not intrusive in any way.

 

[Audioent]

Hello,
amirm said:
"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."

I have Topping A90 amplifier.

Its specs are here: https://hifigo.com/products/topping-a90-full-balanced-headphone-amplifier-amp-xlr-pre-amplifier

Is it O.K. to connect SMSL SU-9 to Topping A90 amplifier?
Are the impedances that amirm has mentioned suitable for connecting the SMSL SU-9 to Topping A90 amplifier?
Thank you

 

[cursive]

Hello,
amirm said:
"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."

I have Topping A90 amplifier.

Its specs are here: https://hifigo.com/products/topping-a90-full-balanced-headphone-amplifier-amp-xlr-pre-amplifier

Is it O.K. to connect SMSL SU-9 to Topping A90 amplifier?
Are the impedances that amirm has mentioned suitable for connecting the SMSL SU-9 to Topping A90 amplifier?
Thank you

Took a bit of hunting but I found a comment from @JohnYang1997, the amazing designer of Topping a90, and he states the input impedance of a90 is "10k for RCA. 2k for XLR" So honestly I'm not so sure about pairing it over XLR. Maybe someone with more knowledge can chime in and let us know what the actual effects would be.

It's in the WolfX700 measurement thread for the a90
https://www.audiosciencereview.com/...nt-of-topping-a90-headphone-amp.11946/page-21