SMSL SU-1 Stereo DAC Review

[2chLover]

You're wrong in your opinion, or rather, you've long since been out of date.
I used to think that too, and it was justified. I'm now even replacing linear power supplies with filtered SMPS.
The wall wart filter from the diyaudio forum gets a cleaner output voltage from a simple switching power supply than your linear power supply delivers. Much smaller, less effort, more gain.

I don't think I'm wrong or have outdated views and solutions. IMHO, it's better to design and use a good, stable, and low-noise power supply without interference than to use a bad power supply and then try to improve its poor DC voltage with some kind of filter.
And your bad power supply with your filter certainly won't beat the near-perfect DC voltage of my circuit. First, read up on the LT3042 I used. Likewise, space and effort weren't a factor in my solution.
But sure, dance your own dance and be happy.

 

[Bwaslo]

You do know that a "linear" power supply isn't linear, I assume? It's a 50 or 60 Hz (or 100Hz or 120Hz) switching supply with harmonic noise throughout the audio band before filtering. I'd rather have the switching frequency well above the audio band, but that's just my take

 

[2chLover]

You do know that a "linear" power supply isn't linear, I assume? It's a 50 or 60 Hz (or 100Hz or 120Hz) switching supply with harmonic noise throughout the audio band before filtering. I'd rather have the switching frequency well above the audio band, but that's just my take

Why don't you at least inform yourself about the LT3042 before answering?
Click here!
...
* Ultralow RMS Noise: 0.8μVRMS (10Hz to 100kHz)
* Ultralow Spot Noise: 2nV/√Hz at 10kHz
* Ultrahigh PSRR: 79dB at 1MHz
...
And I'd rather have no switching frequency...

 

[Bwaslo]

Other than the 50, 60, 100, or 120Hz switching frequency, right?
And its transformer radiating those frequency fields.
Unless you're powering from a battery of course.

I can hear zero noise from any of my SMPS powered audio setups under any circumstances so not really an issue anyway. Any decent electronics will have a PSRR itself. Other than possibility of "linear" transformer acoustic buzz (which I have heard and ditched an amp long ago because of), supply noise is pretty much a solved problem.

 

[2chLover]

I'm still trying to understand what problem you're having with my circuit... You can't generate DC voltage much better than this.
Or is it a fanboy problem?

 

[Bwaslo]

I have no problem with your circuit AT ALL! Nor with an SMPS that causes no audible issues. Both should be dead quiet I imagine.

Just saying if "switching" is a philosophical bugaboo for anyone, then a 50/60 Hz line transformer doesn't do it either.

 

[Roland68]

I don't think I'm wrong or have outdated views and solutions. IMHO, it's better to design and use a good, stable, and low-noise power supply without interference than to use a bad power supply and then try to improve its poor DC voltage with some kind of filter.
And your bad power supply with your filter certainly won't beat the near-perfect DC voltage of my circuit. First, read up on the LT3042 I used. Likewise, space and effort weren't a factor in my solution.
But sure, dance your own dance and be happy.

Developed?
Then please excuse me, I only saw the LHY Audio LT3045 board in the pictures and that's why I wrote about it. We had that board once, too, and the performance wasn't great, which is due to the simple circuit with cheap components and the power transistor. These Chinese companies usually only provide the values from the datasheets and not those of their circuits.

Every power supply needs to be filtered; what matters is the result.
I said goodbye to the LT3042 a long time ago.

 

[2chLover]

Every power supply needs to be filtered; what matters is the result.
Right. And it's almost impossible to achieve a better DC voltage than using an LT3042, or it would be pointless. In my case, I could have used a simple 7805 or something similar, and it would have served the purpose just as well.

BTW, could you please give me some links to the measurement results of the filter mentioned here? Maybe I'll see a potential application for it someday.

 

[Roland68]

Every power supply needs to be filtered; what matters is the result.
Right. And it's almost impossible to achieve a better DC voltage than using an LT3042, or it would be pointless. In my case, I could have used a simple 7805 or something similar, and it would have served the purpose just as well.

BTW, could you please give me some links to the measurement results of the filter mentioned here? Maybe I'll see a potential application for it someday.

Just check out the diyaudio forum; there you'll find numerous topics and circuits related to filters and low-noise circuits for power supplies. One of the filters is also sold as a kit in the shop.

 

[maudio]

SMSL SU-1 in good company

fed by Mutec MC3+ by light signals
feeding another Chinese serene preamp

 

[T-4n14]

My SMSL SU-1 has a static or white noise. The music is barely audible. The SU-1 worked well for a few months. A USB to Toslink/Coaxial converter was added to the system, and sometime after that, the issue started. At first, the issue was on and off; nowadays SU-1 is just not usable. I am attaching a link for a video I made showing the issue.

 

[Roland68]

My SMSL SU-1 has a static or white noise. The music is barely audible. The SU-1 worked well for a few months. A USB to Toslink/Coaxial converter was added to the system, and sometime after that, the issue started. At first, the issue was on and off; nowadays SU-1 is just not usable. I am attaching a link for a video I made showing the issue.

Is it also much quieter?
Then it could be a known problem with the 5V -> +/- 12V voltage converter failing. It's prone to breaking.
If it's under warranty, have it replaced. Otherwise, you can replace it yourself for a few euros if you have soldering experience.

 

[T-4n14]

Is it also much quieter?
Then it could be a known problem with the 5V -> +/- 12V voltage converter failing. It's prone to breaking.
If it's under warranty, have it replaced. Otherwise, you can replace it yourself for a few euros if you have soldering experience.

Yes indeed. The volume goes down. Thank you for advice. I searched online the voltage converter but did not have much luck. There is a discussion on page 33, though not really about the issue I have. Probably I will cut my loses and move on to order something similar, maybe Fosi ZD3 or ZF3.

 

[Monster]

Yes indeed. The volume goes down. Thank you for advice. I searched online the voltage converter but did not have much luck. There is a discussion on page 33, though not really about the issue I have. Probably I will cut my loses and move on to order something similar, maybe Fosi ZD3 or ZF3.

If you want something with similar performance and price point, you could go with a Fosi Audio Q6. That's what I did when I received a faulty SMSL SU-1 from an online retailer.

The styling is pretty bland and the desktop footprint somewhat larger but otherwise it's fine.

 

[theREALdotnet]

If you want something with similar performance and price point, you could go with a Fosi Audio Q6. That's what I did when I received a faulty SMSL SU-1 from an online retailer.

The styling is pretty bland and the desktop footprint somewhat larger but otherwise it's fine.

By and large that seems like the same class of device, likely using very similar internals. Do you have reason to believe it'll be more durable than the SU-1?

 

[Monster]

By and large that seems like the same class of device, likely using very similar internals. Do you have reason to believe it'll be more durable than the SU-1?

Well, I like the performance of SMSL kit, when it works. I think my SMSL C100 is fantastic. However, I have had three pieces of SMSL kit since I got back into music and audio and two out of three have failed.

The first was my C100, bought new from Amazon in Dec 2023 and still going strong. The second was an SMSL B2 bluetooth receiver, bought new from Amazon in Jan 2023 and died four months later (refunded by Amazon). The Third was an SMSL SU-1, bought 'lightly used' from eBay in July 2025 which was DOA (refunded by the seller).

I have two Fosi Audio devices, the Q6 DAC (another eBay 'lightly used' item) and a BT10A amp. Both bought this year and still working. So the sample sizes are small and probably not statistically meaningful but in my very limited experience, Fosi kit seems more reliable than SMSL kit. Coupled with the fact that the SU-1 has a known common failure mode with the 5v to 12v converter chip (not the fault on my SU-1) I think it is likely the Q6 will be more durable than an SU-1.

I should add that some reviewers on Amazon have had trouble with clicks on track changes with the Fosi Q6. This is apparently fixed using a firmware upgrade from Fosi. I use the Q6 coupled to a Wiim Pro via coax and I haven't noticed this problem.

 

[Roland68]

Well, I like the performance of SMSL kit, when it works. I think my SMSL C100 is fantastic. However, I have had three pieces of SMSL kit since I got back into music and audio and two out of three have failed.

The first was my C100, bought new from Amazon in Dec 2023 and still going strong. The second was an SMSL B2 bluetooth receiver, bought new from Amazon in Jan 2023 and died four months later (refunded by Amazon). The Third was an SMSL SU-1, bought 'lightly used' from eBay in July 2025 which was DOA (refunded by the seller).

I have two Fosi Audio devices, the Q6 DAC (another eBay 'lightly used' item) and a BT10A amp. Both bought this year and still working. So the sample sizes are small and probably not statistically meaningful but in my very limited experience, Fosi kit seems more reliable than SMSL kit. Coupled with the fact that the SU-1 has a known common failure mode with the 5v to 12v converter chip (not the fault on my SU-1) I think it is likely the Q6 will be more durable than an SU-1.

I should add that some reviewers on Amazon have had trouble with clicks on track changes. This is apparently fixed using a firmware upgrade from Fosi. I use the Q6 coupled to a Wiim Pro via coax and I haven't noticed this problem.

It should be noted that, in my observation, the encapsulated DC/DCs branded with SMSL and devices with these very cheap switching power supplies (recognizable by the construction of individual components directly on the DAC board) are more often DOA or fail within weeks to two years.
It should be clear that SMSL only does this to save €2-5 on production costs, because it can't be more than that. An end customer can buy the DC/DC converters for €4, the switching power supplies for €7-10. These parts cost a manufacturer about half that, or less. So how great is the potential savings?

For reputable and experienced manufacturers, these parts have a MTBF of at least 12 years in 24/7 operation, often much longer.
SMSL certainly has significantly less experience with building DC/DCs and its own power supplies than 1% of manufacturers like Murata or Mean Well. And there is certainly no way to test such parts for two years and make them fail-safe.
Everyone can draw their own conclusions from this.

 

[Watt768]

Is it also much quieter?
Then it could be a known problem with the 5V -> +/- 12V voltage converter failing. It's prone to breaking.
If it's under warranty, have it replaced. Otherwise, you can replace it yourself for a few euros if you have soldering experience.

Hi!
What could I replace it with that’s pin-compatible and low-noise? My DC-DC also broke, negative rail got shorted — my own fault

 

[Alexium]

Can I hear an improvement? I don't think so. But I feel better now!

This is very honest, and sums up the audio hobby nicely. Also, well done!

 

[Roland68]

Hi!
What could I replace it with that’s pin-compatible and low-noise? My DC-DC also broke, negative rail got shorted — my own fault

You'll find a lot of information about this from post #1,349 to #1,369.
In post #1,363, there's also a link to an inexpensive 2-watt module on Aliexpress.
I would generally recommend a 2-watt module as a replacement.