SMSL SU-1 Stereo DAC Review

[The Capstan]

I use the device with Daphile on a mini PC and I have not encountered any problems. For me It has great sound.

I’ve just purchased an SMSL SU-1 to complete a chain that lets me re-use my old Behringer DEQ2496 for REW room correction.

My setup is:
Daphile (Dell 5070) → USB → Topping D10s (used as USB-to-Toslink bridge) → optical Toslink → DEQ2496 → Toslink out → SMSL SU-1 → analog out to the amp.
Everything works fine except when the sampling rate changes (within the DEQ limit of 96 kHz). For example, switching from 44.1 kHz to 96 kHz causes the SU-1 to briefly mute, unmute, mute again, and then lock — all within a fraction of a second, but very noticeable and quite annoying in practice.

My guess is that the PLL is slow to lock to the new clock rate.
What’s interesting is that feeding the exact same Toslink stream into a different DAC works perfectly, with no dropouts at all.
For this reason, I’m not happy with the SU-1 in my setup and will be returning it to Amazon.

Has anyone got similar experience?

 

[Roland68]

I’ve just purchased an SMSL SU-1 to complete a chain that lets me re-use my old Behringer DEQ2496 for REW room correction.

My setup is:
Daphile (Dell 5070) → USB → Topping D10s (used as USB-to-Toslink bridge) → optical Toslink → DEQ2496 → Toslink out → SMSL SU-1 → analog out to the amp.
Everything works fine except when the sampling rate changes (within the DEQ limit of 96 kHz). For example, switching from 44.1 kHz to 96 kHz causes the SU-1 to briefly mute, unmute, mute again, and then lock — all within a fraction of a second, but very noticeable and quite annoying in practice.

My guess is that the PLL is slow to lock to the new clock rate.
What’s interesting is that feeding the exact same Toslink stream into a different DAC works perfectly, with no dropouts at all.
For this reason, I’m not happy with the SU-1 in my setup and will be returning it to Amazon.

Has anyone got similar experience?

You could try the new SU-2.
USB has been removed, and the inputs for SPDIF Coax, Toslink, and AES have been optimized.
The SU-2 might work better with the DEQ2496, possibly even via AES.

 

[The Capstan]

Thanks Roland.
That’s a possibility. Honestly I don’t like the lack of USB interface. Very limiting nowadays.

 

[Crook]

I'm looking for a dac for desktop with a wiim mini and topping l30ii. I assume I can't really do better, at this price point (no reason to pay more it seems). Thanks.

 

[Roland68]

Thanks Roland.
That’s a possibility. Honestly I don’t like the lack of USB interface. Very limiting nowadays.

USB functionality can be easily implemented with inexpensive DDCs like the PO100, PO100 Pro, PO100 AK, or Douk Audio U2 Pro, offering a significant advantage over other USB-based DACs. The Toslink connection provides true galvanic isolation, eliminating the need for additional investments in case of grounding issues.

For €140–170, you can get one of the most affordable balanced USB DACs with galvanic isolation and an AES/EBU interface. Currently, this is unbeatable in terms of price and performance.

 

[rtraideo]

I’ve just purchased an SMSL SU-1 to complete a chain that lets me re-use my old Behringer DEQ2496 for REW room correction.

My setup is:
Daphile (Dell 5070) → USB → Topping D10s (used as USB-to-Toslink bridge) → optical Toslink → DEQ2496 → Toslink out → SMSL SU-1 → analog out to the amp.
Everything works fine except when the sampling rate changes (within the DEQ limit of 96 kHz). For example, switching from 44.1 kHz to 96 kHz causes the SU-1 to briefly mute, unmute, mute again, and then lock — all within a fraction of a second, but very noticeable and quite annoying in practice.

My guess is that the PLL is slow to lock to the new clock rate.
What’s interesting is that feeding the exact same Toslink stream into a different DAC works perfectly, with no dropouts at all.
For this reason, I’m not happy with the SU-1 in my setup and will be returning it to Amazon.

Has anyone got similar experience?

I wonder if this could be why the SU-1 is slow to start from a stop even over USB.

I'm curious if you've had any issues with the D10s as I'm thinking of grabbing one of those to use as a DAC. Feeding it with a 5070 running Linux (Debian + mpd) as well.

 

[The Capstan]

I wonder if this could be why the SU-1 is slow to start from a stop even over USB.

I'm curious if you've had any issues with the D10s as I'm thinking of grabbing one of those to use as a DAC. Feeding it with a 5070 running Linux (Debian + mpd) as well.

The D10s is a very well designed device.
I am using with Daphile (also Linux based) and it works perfectly.
Very versatile thanks to the toslink bridge functionality. Highly recommended.

In the meanwhile I have got official answer from Shenzenaudio about the SU-1 issue, a bit disappointing but it is what I was expecting…

“Hi there,

The technician replied that this is how it was designed. There is currently no firmware update available.

Best regards”

 

[rtraideo]

The D10s is a very well designed device.
I am using with Daphile (also Linux based) and it works perfectly.
Very versatile thanks to the toslink bridge functionality. Highly recommended.

Thanks. I think I will get one just to have something that always works.

In the meanwhile I have got official answer from Shenzenaudio about the SU-1 issue, a bit disappointing but it is what I was expecting…

“Hi there,

The technician replied that this is how it was designed. There is currently no firmware update available.

Best regards”

Yeah - it's a real shame to see issues like these accepted by consumers. They were solved problems not that long ago, even in ultra cheap implementations. Now they seem to be considered acceptable below a certain price point.

 

[rtraideo]

I bought one of these but I'm sending it back to Amazon. Can't get past the issue of it shutting off the output to save power when connected to USB under Linux and then missing a portion of the audio before it comes back on with a couple of pops (barely audible or loud depending on what's hooked up downstream). You name it I probably tried it, or dismissed trying it because the hack sacrificed bit perfection.

It's too bad this tiny little implementation oversight lets it down. And that the SU-2 solves it by dropping USB altogether!

As a result of the frustration with this DAC and seeing similar user reports for a few other DACs under Linux, I put together a test which I documented in this linked post:

DAC track handling test under Linux

PREFACE Track handling issues of DACs under Linux have been a source of frustration. By track handling issues, I refer to the following: slow to "wake up" when cold starting a track, resulting in missing the starting few hundred milliseconds of the track spurious noises when cold starting or...

www.audiosciencereview.com

 

[Rotel75]

Had audio dropouts every minute when I tried with an old bananapi (armbian) recently.
Guess I'll stick with my Win10 mini PC. It's been super reliable using the ASIO driver and Lyrion Music Server.

 

[maxiuca]

A word of caution:
my unit died two days ago from an electrostatic discharge from my hand. I live in Central Europe, where it’s been quite cold recently and the air is very dry (even with humidifiers running), which leads to static buildup. I used to live in LA, where dry air was also an issue (though not the cold ), but I never had a device fail because of it.

So while it’s a great little device - I really loved it while it worked - it may not be ideal for people living in very dry climates.

 

[Armstrongracer]

Iv'e just purchased a barely used SU-1 second hand (so no warranty). Plan to use it as part of a network streamer feeding analogue signal into a Musical Fidelity amplifier. Source will be a Pi2aes audio dac hat on a Rasberry Pi4. Power to the SU-1 will be from a 5V linear PSU which I have already to supply the Pi2aes. Some questions:

Audio hat has a wide selection of outputs: AES coax, AES XLR (balanced), SPDIF Digital Coax, Toslink Opto. My current thinking for input to the SU-1 is either SPDIF or Toslink. What is the consensus on here about relative sound quality of these two inputs in the SU-1. Also, I'll mainly be streaming High res Tidal via Roon & Ropiee.

Also I've read quite a few posts about early failures with the finger being pointed at the DC/DC converter which seems entirely plausible, especially with 1w rating. Any feedback as to life of the SU-1 after this was replaced or isn't there enough history yet for a definitive opinion?

 

[staticV3]

Hi @Armstrongracer! Welcome to ASR.

Audio hat has a wide selection of outputs: AES coax, AES XLR (balanced), SPDIF Digital Coax, Toslink Opto. My current thinking for input to the SU-1 is either SPDIF or Toslink. What is the consensus on here about relative sound quality of these two inputs in the SU-1. Also, I'll mainly be streaming High res Tidal via Roon & Ropiee.

No difference in the transmitted data (and hence sound quality), except that Toslink has the unique advantage of galvanic isolation which breaks ground loops.

Therefore I'd use Toslink.

 

[SDX-LV]

Could someone confirm if the SU-1 turns-ON without pressing any buttons back to last selected input (Toslink) when you power it on from a charger?
Just if it is sitting behind a TV on a common power strip - I hope I will never need to reach and press the button after cutting power

 

[magreen]

Could someone confirm if the SU-1 turns-ON without pressing any buttons back to last selected input (Toslink) when you power it on from a charger?
Just if it is sitting behind a TV on a common power strip - I hope I will never need to reach and press the button after cutting power

Mine does. I use it exactly that way, on a power strip with a power cutoff switch.

 

[theREALdotnet]

My SU-1s do, too. I have three of them on a multi-port USB charger that is powered on and off via remote control.

 

[half_dog]

@SMSL-Mandy

Sorry if it has been already addressed either I'm asking too much, but I was testing the SU-1 and I noticed it is configured with Short Delay Sharp Roll-Off Filter (at least my unit). Is there any firmware upgrade (or "sidegrade") that could change it to the Sharp Roll-Off Filter?

 

[BenF]

I bought one of these but I'm sending it back to Amazon. Can't get past the issue of it shutting off the output to save power when connected to USB under Linux and then missing a portion of the audio before it comes back on with a couple of pops (barely audible or loud depending on what's hooked up downstream). You name it I probably tried it, or dismissed trying it because the hack sacrificed bit perfection.

It's too bad this tiny little implementation oversight lets it down. And that the SU-2 solves it by dropping USB altogether!

Under what circumstances is your unit's output shutting off? My unit doesn't shut off. I'm using it with Fedora Workstation and I'm very happy with it.

 

[Toku]

All types of Linux use the same underlying kernel modules. There are only a few options ALSA or pulseaudio or pipewire. I had these issues using ALSA which has been around the longest of these. Maybe the others work better but as I understand it pulseaudio will have a software mixer and it won't be bit perfect for that reason. I haven't tried pipewire.

Can you describe the set up on your Linux PCs? I used two different computers with two different distributions using ALSA and did not have any success. The DAC behaved the same through all of the tests.

I have installed Linux on two old PCs and use SU-1, but I never experience any of these symptoms.
I have installed and enjoyed many different types of Linux, including Linux Mint, Q4OS, Zorin OS, and MX linux.
I think the cause is probably due to the configuration of your LINUX system.

 

[SDX-LV]

Anyone tried feeding the SU-1 coaxial input with AES/EBU signal?

AES/EBU can have Voltage up to 7 Vpp while normally SPDIF input is supposed to get about 0.5Vpp. Would I fry coax input on SU-1 with 7Volt signal or it does not care?