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SMSL SU-1 Stereo DAC Review

Rate this DAC:

  • 1. Poor (headless panther)

    Votes: 11 2.1%
  • 2. Not terrible (postman panther)

    Votes: 11 2.1%
  • 3. Fine (happy panther)

    Votes: 64 12.5%
  • 4. Great (golfing panther)

    Votes: 427 83.2%

  • Total voters
    513
Hi all! I just bought this DAC to use with my PC and wanted to add my experience to the pile!

Using USB from my PC, even only for power, doesn't seem to give a good result, I tried:
  • USB for power and audio - sounds like ass, noticeable buzzing/crackling in the output
  • USB from PC only for power + optical for audio - same issue
  • Power from a phone charger + optical for audio - sounds AMAZING
So I can't really recommend this DAC for use with, for example, laptops, where USB is the only option. External power + optical sounds great.
 
Hi all! I just bought this DAC to use with my PC and wanted to add my experience to the pile!

Using USB from my PC, even only for power, doesn't seem to give a good result, I tried:
  • USB for power and audio - sounds like ass, noticeable buzzing/crackling in the output
  • USB from PC only for power + optical for audio - same issue
  • Power from a phone charger + optical for audio - sounds AMAZING
So I can't really recommend this DAC for use with, for example, laptops, where USB is the only option. External power + optical sounds great.
Ground loops. With other USB dacs w/o GBR (somewhere in amp usually) you will hear the same. It's not a DAC issue if you hear buzzing, I guess you hear it w/o playing anything via the DAC.
 
PC USB power can be ok, but I don't trust it. I use a USB power/data splitter and linear power supply.
I wish the DAC makers would always give the option to power separately!
 

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PC USB power can be ok, but I don't trust it. I use a USB power/data splitter and linear power supply.
I wish the DAC makers would always give the option to power separately!
I agree. I use a Douk U2 Pro, with external power supply, to receive USB from my PC. And then optical out from the Douk to my DAC (Chord Mojo). Works like a charm and solved all my noise issues.
 
For some it's probably a feature, but for me it's a bug.
When switching to opt/coax, the USB device is disabled.
Streaming software does not like disappearing devices!
This behaviour should be configureable. @SMSL-Mandy
 
Hi all! I just bought this DAC to use with my PC and wanted to add my experience to the pile!

Using USB from my PC, even only for power, doesn't seem to give a good result, I tried:
  • USB for power and audio - sounds like ass, noticeable buzzing/crackling in the output
  • USB from PC only for power + optical for audio - same issue
  • Power from a phone charger + optical for audio - sounds AMAZING
So I can't really recommend this DAC for use with, for example, laptops, where USB is the only option. External power + optical sounds great.
I've been using it with my laptop for around 9 months without any issue, wonder what the problem might be on your end
 
Feeding from USB power of digital source is absolutely OK. These USB DACs like the SU-1 has multiple internal SMPS, filtering and high-grade reference voltage regulators. They has very good PSRR, so has a lot of immunity to noise. If you see the PCB DAC, receiving voltage from USB is filetered by many capacitors, coils and then going to the internal SMPS. It can handle well noisy USB supply, even so designed to do it to provide 110dBm+ SINAD. So, most probably you degrade the whole system SINAD more by introducing ground loops. Even @amirm says he is not using high-grade or dedicated PS during measurements. Feeding via SPDIF/optical just reduce the groundloops in your system.
 
Maybe already mentioned, but the recent XMOS-USB driver on SMSL's site allows the 'Always On' option in the control panel (no need to edit the 'XMOSUSBDACCpl.xml' as with the previous version). Might actually default to 'Always On' (rather than 'On When Needed'), I can't remember if I had to change it.
 
Feeding from USB power of digital source is absolutely OK. These USB DACs like the SU-1 has multiple internal SMPS, filtering and high-grade reference voltage regulators. They has very good PSRR, so has a lot of immunity to noise. If you see the PCB DAC, receiving voltage from USB is filetered by many capacitors, coils and then going to the internal SMPS. It can handle well noisy USB supply, even so designed to do it to provide 110dBm+ SINAD. So, most probably you degrade the whole system SINAD more by introducing ground loops. Even @amirm says he is not using high-grade or dedicated PS during measurements. Feeding via SPDIF/optical just reduce the groundloops in your system.
Using a 'Class 2' PSU for the amplifier, i.e. one with a two-pin AC inlet (no ground) usually pre-empts noise problems with USB DACS. I get a lot of noise from the SU-1 or any other USB interface from the GPU and USB mouse in my PC with a Class 1, from both speaker and headphone amps, completely silent with Class 2.
 
Hi all! I just bought this DAC to use with my PC and wanted to add my experience to the pile!

Using USB from my PC, even only for power, doesn't seem to give a good result, I tried:
  • USB for power and audio - sounds like ass, noticeable buzzing/crackling in the output
  • USB from PC only for power + optical for audio - same issue
  • Power from a phone charger + optical for audio - sounds AMAZING
So I can't really recommend this DAC for use with, for example, laptops, where USB is the only option. External power + optical sounds great.
^^^ See above.
 
Using a 'Class 2' PSU for the amplifier, i.e. one with a two-pin AC inlet (no ground) usually pre-empts noise problems with USB DACS. I get a lot of noise from the SU-1 or any other USB interface from the GPU and USB mouse in my PC with a Class 1, from both speaker and headphone amps, completely silent with Class 2.
Typical ground loop issue through AC ground. I'm building amps, faced with it. The "floating" ground with double-insulated (class2) PS/devices you mentioned is one solution. The problem how to solve it when you have different DAC, typically upper-level w/ internal low-noise SMPS where the whole device house AC grounded. But, it's not the SMPS problem. There are solutions like "ground lifting" using diode-bridge + 100nF C, and some parallel 100ohm GBR, typically at amplifier side....
 
Typical ground loop issue through AC ground. I'm building amps, faced with it. The "floating" ground with double-insulated (class2) PS/devices you mentioned is one solution. The problem how to solve it when you have different DAC, typically upper-level w/ internal low-noise SMPS where the whole device house AC grounded. But, it's not the SMPS problem. There are solutions like "ground lifting" using diode-bridge + 100nF C, and some parallel 100ohm GBR, typically at amplifier side....
I've just ordered a new, high-quality Mean Well GST120A24 (24V/5A) Class 1 PSU (at a bargain price - from RS it would have been £50, from Farnell no less than £80!) to go with a new speaker amp on its way, so I'll need to sort out the ground loop. Fortunately I have a ifi 'iDefender' I bought a couple of years back when I was wrestling with the problem, but had sorted it with Class II PSU's by the time it arrived. Fingers crossed it'll work.
 
I've just ordered a new, high-quality Mean Well GST120A24 (24V/5A) Class 1 PSU (at a bargain price - from RS it would have been £50, from Farnell no less than £80!) to go with a new speaker amp on its way, so I'll need to sort out the ground loop. Fortunately I have a ifi 'iDefender' I bought a couple of years back when I was wrestling with the problem, but had sorted it with Class II PSU's by the time it arrived. Fingers crossed it'll work.
I hope so, but the ground loops are not affected by the PSU quality, if the PSU is class1, it cannot do anything with the loop. It should be eliminated at amplifier side, we have many ways usually at amp/preamp side how to do it, some amps has switches at the back side how to handle AC ground.
 
I hope so, but the ground loops are not affected by the PSU quality, if the PSU is class1, it cannot do anything with the loop. It should be eliminated at amplifier side, we have many ways usually at amp/preamp side how to do it, some amps has switches at the back side how to handle AC ground.
Yah, I only mentioned the PSU quality because it's tempting to take chances with no-name wall-warts/bricks and I'm a leave everything powered on 24/7 (where feasible) guy.
 
I made a video of my USB issue.
Is my SU-1 broken?
Is my setup strange?
Is this normal for the SU-1?
Do other DAC also disabled the USB when switching inputs?
Why isn't this mentioned in reviews?
 
I made a video of my USB issue.
Is my SU-1 broken?
Is my setup strange?
Is this normal for the SU-1?
Do other DAC also disabled the USB when switching inputs?
Why isn't this mentioned in reviews?
Presumably the USB controller is taken out of circuit or switched off when selecting SPDIF on the DAC.

If your concern is being able to configure bit-depth/sample rate in Windows, it will now be the PC's on-board SPDIF out - open 'Sound' > 'Sound Control Panel' and it will be something like 'Realtek Digital Output'. That will be for all DirectSound applications. If you use ASIO or WASAPI in something like Foobar the PCM is passed straight to the DAC within the limits of SPDIF, but that's most up to 24/192 stereo.

ETA > direct access to Windows 'Sound Control Panel' stopped with Win 10, you can't even find it with 'search' (thanks M$, you idiots), you now have to create a shortcut which I've done - forgotten how, search for something like "create shortcut Windows sound-control-panel".
 
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There are plenty of bugs features to be discovered playing with these capable but let's face it cheep DACS - I just discovered that sometimes if I switch the SMSL Sanskrit III (very similar to the SU-1 but with volume control/digital attenuation) to SPDIF and back to USB - no sound. Switching it off and on again (!) sorts it (tried rebooting first and that didn't work).

One of those fun, fun, fun, heart-in-mouth moments wondering if I was facing having to deal with SMSL or the Chinese seller I bought it from.

ETA >> LoL - I've discovered, on the tail of the above;

if you have the Sanskrit III's display disabled and switch it off and on again, the power indicator (normally blue for on, red for off) goes out. The digital display still lights up for a few seconds for button presses on the remote as normal. For me that really is a bug that's a feature, I like having it completely dark.

In fairness, I have to wonder if it's an 'Easter egg' deliberately configured by SMSL. Whatever, it's actually welcome.
 
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So here the two videos about the USB issues...

1) input switch disables USB: code/firmware decision by SMSL, or basic XMOS feature?

2) Squeezelite-X USB crash when using ASIO: XMOS driver or usb bug?
 
So here the two videos about the USB issues...

1) input switch disables USB: code/firmware decision by SMSL, or basic XMOS feature?

2) Squeezelite-X USB crash when using ASIO: XMOS driver or usb bug?
I know, it's not helping you, but on Ubuntu Linux 22.04 there are no such issues. I'm using with ALSA direct streaming to device, switch on/off, plug in/out, changing inpuz does nothing, if on USB kernel starts using it.
It's an another story, if using direct ALSA streaming to the audio device, the Audacious get stuck (frozen) if I remove/switch USB audio device during playback, but IMHO it's normal.
 
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