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SMSL D300 Review (Balanced DAC)

amirm

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This is a review and detailed measurements of the new SMSL D300 stereo USB DAC. It was sent to me by the company and costs US $399.99.

I am pleased with the refinements of LCD and controls:

SMSL D300 Review Balanced Stereo USB DAC.jpg


The LCD no longer has that fuzzy look of prior SMSL products. And the flush mounted buttons look more modern and elegant.

Digging inside, this is the first DAC we are testing that is powered by the ROHM BD34301EKV. I know of RHOM as a manufacturer of discrete products (e.g. resistors). Had no idea they had gotten into high-performance audio IC business. So it will be interesting to see if it is competitive with ESS to give us another alternative in the market (with AKM out of business currently).

Back panel is typical of products of this class:

SMSL D300 Review Back Panel Bluetooth Balanced Stereo USB DAC.jpg


A remote control is provided which lets you adjust various options and volume control.

SMSL D300 Measurements
Let's start with our dashboard using XLR Output:
SMSL D300 Measurements Balanced Stereo USB DAC.png


Very nice. Not at the top of the class but ranks way up there among some 350 DACs tested to date:

Best USB DAC Reviewed.png


Zooming in:


Best USB DAC Reviewed zoom.png


We lose a bit of performance as usual when switching to RCA out:

SMSL D300 Measurements Unbalanced Stereo USB DAC.png


Distortion in either case is at -120 dB which is a few dBs below threshold of hearing. So absolutely transparent in that regard.

Noise performance is excellent:

SMSL D300 Measurements Dynamic Range Balanced Stereo USB DAC.png


IMD distortion is above average as well:

SMSL D300 Measurements IMD Distortion Balanced Stereo USB DAC.png


Multitone shows vanishingly low distortion:
SMSL D300 Measurements Multitone Balanced Stereo USB DAC.png


Jitter test fair bit of unwanted tones but fortunately they are well below audibility:

SMSL D300 Measurements Jitter Balanced Stereo USB DAC.png


Only two filters are provided:

SMSL D300 Measurements Filter Response Balanced Stereo USB DAC.png


Linearity is perfect:
SMSL D300 Measurements Linearity Balanced Stereo USB DAC.png


Noise and distortion with 90 kHz measurement bandwidth shows elevated level:
SMSL D300 Measurements THD+N vs Frequency Balanced Stereo USB DAC.png


This doesn't mean it is audible increase though. Let's see where it comes from by examining the spectrum to 90 kHz:

SMSL D300 Measurements FFT Balanced Stereo USB DAC.png


As I guessed, it uses "noise shaping" to push audible noise into ultrasonic range. This is the right trade off to increase usable signal to noise ratio. But then messes up the "optics" of our previous THD+N vs frequency.

FYI there is a curious "HPC" mode in this DAC. It changes the accuracy of the FIR reconstruction filters. I turned it on and off in the dashboard and a couple of other tests but it did not show anything. I will have to think about a specific test to bring out its value.

Conclusions
It is refreshing to both see the refined look of SMSL desktop products in this DAC and use of a new option in DAC chip technology. Performance is excellent but shy of state of the art.

I am going to put the SMSL D300 on my recommended list.

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

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Tks

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Not sure why they went with this sort of last-gen case design. I actually liked their new stuff, all they had to do was not have that plastic top (idk, some folks say that's glass?).

How deep does that sharp filter attenuate btw? Never seen one fall down that low.

Also, I had a question. How do some DACs (mostly higher end) have very flat and extremely low THD ratio vs frequency performance, even when they're using sharper filters? They also have great jitter, and basically SNR on top of it all. You say there's noise shaping going on when we see this sort of high THD ratio VS FR metric. Why use it if it's going to produce a result like this?

You have DACs like this that show even the usual "brickwall" filters can be had without that ratio suffering. So my question is, what exactly is account for better performance in the THD Ration VS FR metric. It's not the filter type, as there are filters that do achieve brickwall, but then somewhat fail the ratio metric. Likewise we have somewhat "slowish" filters (terminate later at ~24kHz or a bit beyond) yet they achieve sometimes excellent ratio metrics, and sometimes they don't.

So what's going on here?
 
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amirm

amirm

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Also, I had a question. How do some DACs (mostly higher end) have very flat and extremely low THD ratio vs frequency performance, even when they're using sharper filters?
They have filters with very high attenuation and no noise shaping within 90 kHz band.
 

Tks

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They have filters with very high attenuation and no noise shaping within 90 kHz band.

That's it? So don't noise shape within 90 kHz and provide a brickwall filter? That's all one needs for those flat and low Ratio metric results?
 

H-713

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Interesting that ROHM is making DAC chips...

Other than ESS, what are most of the good DACs using? Cirrus Logic? TI? AD?
 

capslock

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ROhm used to make advanced audio power transistors in the 80s but since, they have been mostly known for their passive components. They make a bunch of standard audio opamps, too. Amazing to see them coming up with a very top of the line DAC out of nowhere.

Regarding other DAC makers, TI has the PCM1792 / 1794 which is good on noise but not stellar on harmonic distortion. It is expensive as a chip (about $14 in singles) and needs three external opamps per channel because it is current out. They have gotten out of the game of top DACs pretty much, as have AD. Cirrus had the CS4398 which was almost on par with the 1792 on HD but significantly worse on noise, but their recent CS43131 is a winner.
 

MC_RME

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I think that 'noise shaping' thing is a misunderstanding. IMHO all DACs do that and also similarly. If you don't see that rise over frequency then the chip itself has an additional or modified output filter to remove it. AKM's 4490 (and all later) was fabulous in that regard, ESS is very good too. Cirrus, even the latest ones, all missed it and have this out-of-band noise rise.
 

H-713

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ROhm used to make advanced audio power transistors in the 80s but since, they have been mostly known for their passive components. They make a bunch of standard audio opamps, too. Amazing to see them coming up with a very top of the line DAC out of nowhere.

Regarding other DAC makers, TI has the PCM1792 / 1794 which is good on noise but not stellar on harmonic distortion. It is expensive as a chip (about $14 in singles) and needs three external opamps per channel because it is current out. They have gotten out of the game of top DACs pretty much, as have AD. Cirrus had the CS4398 which was almost on par with the 1792 on HD but significantly worse on noise, but their recent CS43131 is a winner.
Interesting that AD doesn't sell any... they seem to love selling expensive parts to niche markets.
 

Veri

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Really nice results, especially that multi-tone is ultra clean~
 

GWolfman

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Nice to see some additional & competent competition from another DAC manufacturer.
 

Tangband

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Not sure why they went with this sort of last-gen case design. I actually liked their new stuff, all they had to do was not have that plastic top (idk, some folks say that's glass?).

How deep does that sharp filter attenuate btw? Never seen one fall down that low.

Also, I had a question. How do some DACs (mostly higher end) have very flat and extremely low THD ratio vs frequency performance, even when they're using sharper filters? They also have great jitter, and basically SNR on top of it all. You say there's noise shaping going on when we see this sort of high THD ratio VS FR metric. Why use it if it's going to produce a result like this?

You have DACs like this that show even the usual "brickwall" filters can be had without that ratio suffering. So my question is, what exactly is account for better performance in the THD Ration VS FR metric. It's not the filter type, as there are filters that do achieve brickwall, but then somewhat fail the ratio metric. Likewise we have somewhat "slowish" filters (terminate later at ~24kHz or a bit beyond) yet they achieve sometimes excellent ratio metrics, and sometimes they don't.

So what's going on here?
The SMSL D300 uses a xmos xu208 chip for USB audio. Its a 32 bit device thats also used in the Topping D10s and also in many modern semiprofessional A/D - D/A interfaces.
It seems to offer very low jitter and the ability to create a very good 24 bit ( from 32 bit and dithering ) digital volume regulation .
6F8E7EF2-4B62-4E87-A2AF-D7B49E691DF1.jpeg
 
Last edited:

Veri

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The SMSL D300 uses a xmos xu208 chip for USB audio [...]
It seems to offer very low jitter and the ability to create a very good 24 bit ( from 32 bit and dithering ) digital volume regulation .
The xmos is just the microprocessor used for USB interfacing, by itself you can't tell if a device will have decent or better jitter performance, it is just one piece in the processing/interfacing. Inherently it has no jitter specification. That's up to the device/DAC implementation.
 

pavuol

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Veri

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More ASR threads that preceded this review:
with comments from @SMSL_Liu
 

Lambda

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This was at 0dBFS i assume and at what volume level? "100%"?

Only two filters are provided:
Filters Measured at 0dBFS and full volume? are they clipping?

the first DAC we are testing that is powered by the ROHM BD34301EKV. I know of RHOM as a manufacturer of discrete products (e.g. resistors). Had no idea they had gotten into high-performance audio IC business.
Nice to see something new on the market!
 

holbob

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Didn't SMSL just release a high performing dac in this price point? I get confused they seem to release so many. Maybe I dreamt it. Filters seem average in this one, worthy of criticism?
 

w1000i

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This was at 0dBFS i assume and at what volume level? "100%"?


Filters Measured at 0dBFS and full volume? are they clipping?


Nice to see something new on the market!
There is 2 output mode. One is fixed 4v the other variable reach 4.5V
 
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