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SMSL D300 Review (Balanced DAC)

shadowmdj

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So, I have this strange issue with my D300. I have connected it to my MacBook pro M1 with USB, and it worked flawlessly. After some time, like 30 minutes or so, the DAC disconnected from the computer automatically, and the display displayed 'DSD.' I tried restarting it with its remote, and it connected to the computer again, and the display was showing PCM. But after a minute or two, it disconnected again with the display showing 'DSD'. Then I restarted, and the cycle went on and on.
I thought my Mac might be the culprit. So, I connected it to the USB out of a Raspberry Pi 3 B+ running moode audio, and it didn't connect at all. It was still showing DSD. I restarted the RPI and no joy. It was still showing DSD. I connected another DAC to the RPi and after restarting, it got detected but not my SMSL D300.
After the DAC showed 'DSD,' even if I removed it from the USB port, 'DSD' remained on the screen.

I did reset my D300 and also reinstalled the moode in RPI. Things didn't work out.
Can it be an issue with the DAC itself?

Does anyone have a similar issue with your D300?
 

Snoopy

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So, I have this strange issue with my D300. I have connected it to my MacBook pro M1 with USB, and it worked flawlessly. After some time, like 30 minutes or so, the DAC disconnected from the computer automatically, and the display displayed 'DSD.' I tried restarting it with its remote, and it connected to the computer again, and the display was showing PCM. But after a minute or two, it disconnected again with the display showing 'DSD'. Then I restarted, and the cycle went on and on.
I thought my Mac might be the culprit. So, I connected it to the USB out of a Raspberry Pi 3 B+ running moode audio, and it didn't connect at all. It was still showing DSD. I restarted the RPI and no joy. It was still showing DSD. I connected another DAC to the RPi and after restarting, it got detected but not my SMSL D300.
After the DAC showed 'DSD,' even if I removed it from the USB port, 'DSD' remained on the screen.

I did reset my D300 and also reinstalled the moode in RPI. Things didn't work out.
Can it be an issue with the DAC itself?

Does anyone have a similar issue with your D300?

Nope. Does your MacBook go into energy saving mode maybe? Try the "amphetamine" app.
 

v1adpetrov2

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Sep 24, 2022
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I have rolled back the MCU and now it's back to normal for PRE amp mode again.
V1.0 MCU Hex file attached, just added .zip to file name so I could attach
Thank you very much!!!
I flashed my D300 with your file - the pops disappeared and the preamp functions were restored! :)
If it's not a secret, on which site were you able to find this file?
 

v1adpetrov2

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You have a good distributor!
Once again, THANK YOU VERY MUCH!
But the members SMSL-Mandy and Toku are real provocateurs!
They've caused people problems and now they're sitting like mice under a broom.
After the messages about the glitches of the new firmware began, they never squeaked...
...And they didn't do anything to fix this problem, they didn't even delete the files with the buggy firmware from the post.
 

Kaydee6

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You have a good distributor!
Once again, THANK YOU VERY MUCH!
But the members SMSL-Mandy and Toku are real provocateurs!
They've caused people problems and now they're sitting like mice under a broom.
After the messages about the glitches of the new firmware began, they never squeaked...
...And they didn't do anything to fix this problem, they didn't even delete the files with the buggy firmware from the post.
It shows that other than measuring well, after sales service and subjective listening is just as if not more important.
 

Neric74

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I have rolled back the MCU and now it's back to normal for PRE amp mode again.

Trick is to only attach USB cable AFTER you have the program loaded and the box prevented from booting via the power/ ftn button method

V1.0 MCU Hex file attached, just added .zip to file name so I could attch
Thank you for the file, I was starting to sweat has I wrongly updated too quickly the MCU file, before reading of the issues it will cause down the road, thanks a mill !
 

Happyhammer

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Thank you for the file, I was starting to sweat has I wrongly updated too quickly the MCU file, before reading of the issues it will cause down the road, thanks a mill !
Latest USB and MCU firmware with fix for very loud pops. Added .zip to file names.
Noticed on pre amp mode, when my network streamer (stack audio link 1 running stripped down volumio ) sends DSD direct it shows hires on display and volume can be changed. When it sends DOP, it displays DSD in preamp mode and volume is fixed.
 

Attachments

  • IAP_D300_MM32_1v1.hex.zip
    1.3 MB · Views: 217
  • SMSL D300_USB_DFU v1.3.bin.zip
    28 KB · Views: 208

v1adpetrov2

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Latest USB and MCU firmware with fix for very loud pops.
Thanks for the firmware files!
Downloaded, flashed ...
Yes, that's right, the strong pops disappeared..., but the quiet pops remained. :oops:
I left the new firmware for USB (XMAS) v1.3.
But with the new firmware for MM32F103 v1.11 rolled back to the old firmware v1.0.
I suspect that the old firmware version more correctly controls the 3710 switching keys at the DAC outputs.
SMSL_D300__output_keys_.jpg
Smoothly increases/decreases the output voltage when pressing the "PLAY/STOP" buttons in software players.
And there are no pops.
In firmware v1.11, the keys open immediately, which causes a slight shift of the signal zero and, as a result, a quiet pop.
Moreover, the volume of this pops does not depend on the level of the installed volume of the DAC in the "Pre Mode -> Vol Variable".
 
Last edited:

Happyhammer

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Thanks for the firmware files!
Downloaded, flashed ...
Yes, that's right, the strong pops disappeared..., but the quiet pops remained. :oops:
I left the new firmware for USB (XMAS) v1.3.
But with the new firmware for MM32F103 v1.11 rolled back to the old firmware v1.0.
I suspect that the old firmware version more correctly controls the 3710 switching keys at the DAC outputs.
View attachment 249247
Smoothly increases/decreases the output voltage when pressing the "PLAY/STOP" buttons in software players.
And there are no pops.
In firmware v1.11, the keys open immediately, which causes a slight shift of the signal zero and, as a result, a quiet pop.
Moreover, the volume of this pops does not depend on the level of the installed volume of the DAC in the "Pre Mode -> Vol Variable".
That sounds about right.

I bought an smsl sp400 for preamp and headphone usage so now only use the d300 in fixed volume/DSD mode and of course have no issues in this mode.
 

v1adpetrov2

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That sounds about right.
I bought an smsl sp400 for preamp and headphone usage so now only use the d300 in fixed volume/DSD mode and of course have no issues in this mode.
I probably couldn't get my point across to you:
In my D300 instance with v1.11 firmware installed, quiet pops are present both with "Vol Fixed" and with "Vol Variable", both with the PCM stream and with the DSD stream.
With v1.0 firmware installed, there are no quiet pops.
And in your instance D300 do you have quiet pops with firmware v1.11?

P.S. The main disadvantage of SMSL SP400: XLR-balanced signal is converted to unbalanced and only then gets to the 256 level relay volume control.
Then, after the volume control, the unbalanced signal again is converted into a balanced one and goes to the headphone amplifier and XLR outputs.
SMSL_SP400_scheme_(relay).jpg
 
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Happyhammer

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I probably couldn't get my point across to you:
In my D300 instance with v1.11 firmware installed, quiet pops are present both with "Vol Fixed" and with "Vol Variable", both with the PCM stream and with the DSD stream.
With v1.0 firmware installed, there are no quiet pops.
And in your instance D300 do you have quiet pops with firmware v1.11?

P.S. The main disadvantage of SMSL SP400: XLR-balanced signal is converted to unbalanced and only then gets to the 256 level relay volume control.
Then, after the volume control, the unbalanced signal again is converted into a balanced one and goes to the headphone amplifier and XLR outputs.
View attachment 249305
I have no indepth technical knowledge, do can't comment on the internal workings.

I am only using fixed mode now and can only report in this situation. It appears when advancing from one track to another in the playlist normally, there is absolutely no indication of sound pops. When advancing by pressing fast forward to next track, there may be the slightest of pops that you really need to be listening out for but is totally acceptable to me. Of course there may be are other factors that could affect what users experience, such as what your source hardware/software is as well as what content you are playing.

For my last tests, I was using a stack audio link 1 network streamer with volumio set to send any DSD files over pcm to the D300. The balanced D300 output feeding the sp400 and then listening via either the unbalanced headphone output to a pair of Kennington Magni's or the balanced output to a pair of sabaj A8 monoblock amps and then wharfedale diamond 12.4 floorstanders.
 

v1adpetrov2

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...It appears when advancing from one track to another in the playlist normally, there is absolutely no indication of sound pops. When advancing by pressing fast forward to next track, there may be the slightest of pops that you really need to be listening out for but is totally acceptable to me.
This is exactly the information I wanted to hear from you.

Yes, when switching from track to track in the playlist, there are no quiet pops on all firmware versions.
But in firmware v1.11, when pressing the "STOP/PLAY/NEXT/PREV" keys, quiet pops are present.
If you re-install firmware v1.0, then when you press these keys there are absolutely no claps, but a smooth increase in volume is heard for 50-80msec.
 

Happyhammer

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This is exactly the information I wanted to hear from you.

Yes, when switching from track to track in the playlist, there are no quiet pops on all firmware versions.
But in firmware v1.11, when pressing the "STOP/PLAY/NEXT/PREV" keys, quiet pops are present.
If you re-install firmware v1.0, then when you press these keys there are absolutely no claps, but a smooth increase in volume is heard for 50-80msec.
I guess the most important thing is if you are listening to an album that it plays each track without disruption. Being able to play a mixture of DSD and flac files in the playlist is also important to me.
Rather than jump to a track in the playlist in which you may encounter a low pop, you could of course just move the track up the playlist, assuming your controlling software allows that.
 

Snoopy

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I guess the most important thing is if you are listening to an album that it plays each track without disruption. Being able to play a mixture of DSD and flac files in the playlist is also important to me.
Rather than jump to a track in the playlist in which you may encounter a low pop, you could of course just move the track up the playlist, assuming your controlling software allows that.
Or U just upsample everything to the DSD :)
 

Happyhammer

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Or U just upsample everything to the DSD :)
Yes, but ignoring the audio results of doing that, I simply did not want to have a PC on all the time to do media streaming/ upsampling ( ie roon )and that included a fanless NUC. I would still need to have a USB audio device to reclock so I use the stack audio link 1 to do all the above in a fanless device but with a volumio version that I don't have to pay to use qobuz addon
 

Kw6

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Hi,

I should get my D300 in a few days! I hope I don't have any issues. I read all 14 pages of this thread.
 

pickyAudiophile

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Hi,

I should get my D300 in a few days! I hope I don't have any issues. I read all 14 pages of this thread.
I made these two demo clips at #241 and #242 of this thread. I was able to solve the pop issues by installing firmware rev. 1.0 from #259 - at the expense of split seconds of muting here and there (PCM data, preamp mode, e/g changing sample rate or pausing and playing once again).
You may expect delivery with later (further broken) firmware installed by default. Luckily we now have the tools to do some back-and-forth rolling.
Still there is no firmware available which manages to fix these issues altogether (PCM, DSD, preamp, fixed). Which is not satisfactory at all.
@v1adpetrov2 and @Happyhammer made some truely helpful contributions.
 
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