Fosi Audio DS2 Portable DAC & Amp Review

[Eddie]

Guys, I think we might be blaming the wrong guy this whole time…

After carefully reading every page of the CS43131 chip's document, this part caught my eyes:

View attachment 398062

These settings might actually be the problem, especially the soft ramp and auto mute function.

From what I understand, it takes time for the DAC to get out of the muted state, so it could cause the first half second of the audio to be lost, the auto mute function is the most suspected.

@Fosi Audio Maybe ask your engineers about this, and try to solve this annoyance, it could be as simple as changing literally several bits in your firmware.

As I understand the description, bits 7 and 4-5 only control muting and unmuting when a filter mode changes.
However, Fosi does not offer changing filter modes on the DS2 (unlike the Tanchjim SPACE).
So the filter mode never changes and these three bits are effectively irrelevant.

Bit 3 (auto mute) is indeed problematic if left at the default value of 1 and muting and unmuting results in a click.
If that is the case on the DS2, Fosi should be able to set this bit to 0 via a firmware update.

In the meantime, after some discussion with Fosi they seem to have understood the fade-in issue in WASAPI exclusive mode.
They finally write:
"This issue is being optimized. If there is a new version of the software, we will send it to you as soon as possible."
Whatever that means.

 

[norcalscott]

I finally had my DS2 delivered and it compares favorably against my other DAC/Dongles and the 4.4mm balanced port in addition to the normal 3.5mm is very convenient. One issue I am having, however, is that when using it on my Samsung S21 with USB Audio Player Pro, it disconnects if I pause music, or if my phone's screen goes off. (When random playing a local folder it deletes the play queue, which is annoying) I've tried a few different developer mode settings but nothing seems to prevent these issues. Since I saw where several in this thread are using USBAPP with this DAC/Dongle, I am curious if anyone else has had this issue?

 

[roladyzator]

I finally had my DS2 delivered and it compares favorably against my other DAC/Dongles and the 4.4mm balanced port in addition to the normal 3.5mm is very convenient. One issue I am having, however, is that when using it on my Samsung S21 with USB Audio Player Pro, it disconnects if I pause music, or if my phone's screen goes off. (When random playing a local folder it deletes the play queue, which is annoying) I've tried a few different developer mode settings but nothing seems to prevent these issues. Since I saw where several in this thread are using USBAPP with this DAC/Dongle, I am curious if anyone else has had this issue?

Have you fiddled with the options in the USB Audio Tweaks menu?
You can see if perhaps an increased buffer size or some other option can prevent this.

Also, see if the setting of Release USB audio driver on Home (that's in System part of the settings) makes a difference.

I don't have an issue where the Fosi disconnects, though.
I have an older Samsung, the Note 10 Lite.
My issue are sound dropouts, and there seem to be far less of them if I enable the Samsung's power saving mode (the lighter version, no the one which limits the phone to only selected apps) and disable Bluetooth.

 

[norcalscott]

Have you fiddled with the options in the USB Audio Tweaks menu?
You can see if perhaps an increased buffer size or some other option can prevent this.

Also, see if the setting of Release USB audio driver on Home (that's in System part of the settings) makes a difference.

I don't have an issue where the Fosi disconnects, though.
I have an older Samsung, the Note 10 Lite.
My issue are sound dropouts, and there seem to be far less of them if I enable the Samsung's power saving mode (the lighter version, no the one which limits the phone to only selected apps) and disable Bluetooth.

Yes, played with some of the settings and cannot seem to make it make a difference. I'll try a few more things and if all else fails I'll send a report to the developer - I've done that a couple of times of the years and he is generally very responsive. There could be something about this DAC that will require tweaking the integration.

I haven't experienced drop-outs as long as the songs are playing and the phone's screen is on. When I pause, for example, and walk away for 5-10 minutes, come back and unlock my phone - that is when the DAC is disconnected and my queue gone. Reconnecting the DAC is not too bad of an issue (it does this automatically) but losing the queue is annoying. I will look into the power savings settings (which I have turned off, but there may be more things to tweak there) as this does seem like a power thing.

 

[Psinet]

Do we know if the balanced out on this has a ground yet?

Some of the issues others are experiencing are concerning, also.

 

[Psinet]

Paid for one on the 10th and still waiting for dispatch.

@Fosi Audio are there delays in shipment?

 

[Eddie]

To whom it may concern:

I just received the following email from Fosi regarding the fade-in issue in WASAPI exclusive mode:

"During the sample test, we found a slight POP sound when switching songs/pausing playback.
For a better user experience, we added a mute circuit, which will mute the signal 100ms before it is transmitted to DS2.
At this time, there is no sound. In your window 10 built-in audio test, we also found the same problem.
The software engineer estimated that it was caused by the compatibility of the above mute circuit + window 10 system.
You can test whether the same problem occurs when playing music on a normal music APP.
We estimate that the mute circuit will not have much impact on listening to music.
Thank you."

To me, their estimate is wrong. I returned the DS2 just because of this issue.
This is the third USB dongle audio device with CS43131 in a row that does not work in WASAPI exclusive mode. They either skip the beginning of a track or fade in or both. Personally, I'm done with CS43131 implementations.

I wonder if E1DA 903x behaves correctly in this regard.

 

[AndiGee]

Can you run tools like DPCLatencyChecker or LatencyMon and see the difference between your Windows 10 and Windows 11?

Monitored my Windows 10 and Windows 11 systems using 'LatencyMon'.

Result is that on both systems the NVidia driver has the highest reported execution time and is most likely to affect the real time audio. As expected, the Windows 11 system should be more sufficient for handling real-time audio - which comes to no surprise since its the much newer hardware.

I have also noticed that certain actions - for example, opening the browser for the first time after the first system start, trigger the described sound dropouts more frequently.

In the meantime I also tested the unit on my old Mac Pro running OSX Monterey - no dropouts.

 

[GeekyBastard]

"We estimate that the mute circuit will not have much impact on listening to music. The software engineer estimated that it was caused by the compatibility of the above mute circuit + window 10 system."

@Fosi Audio This is concerning, what does this statement actually means?

“Will not have much impact on listening to music” was such a wildly bold claim, you can't just assume a hardware level bug like this won't affect the user experience.

Will this ever be fixed, or is it not fixable? It is not acceptable to have a “mute circuit” and it's actively causing compatibility issue with the system.

@amirm I think this statement from the manufacture deserves a warning at the first page post.

 

[ObjectiveSubjectivist]

I finally had my DS2 delivered and it compares favorably against my other DAC/Dongles and the 4.4mm balanced port in addition to the normal 3.5mm is very convenient. One issue I am having, however, is that when using it on my Samsung S21 with USB Audio Player Pro, it disconnects if I pause music, or if my phone's screen goes off. (When random playing a local folder it deletes the play queue, which is annoying) I've tried a few different developer mode settings but nothing seems to prevent these issues. Since I saw where several in this thread are using USBAPP with this DAC/Dongle, I am curious if anyone else has had this issue?

I'm using it in the same setup.
Samsung s21 + usb audio player pro (tidal mostly) + fosi.
And I have no issues whatsoever, it must be something with setting on your phone or and audio player pro.
Hope that helps.

 

[norcalscott]

I'm using it in the same setup.
Samsung s21 + usb audio player pro (tidal mostly) + fosi.
And I have no issues whatsoever, it must be something with setting on your phone or and audio player pro.
Hope that helps.

Thanks for the information! It is weird - I am continuing to troubleshoot this and can't see any setting that would cause these problems. I am going to re-install USBAPP and see if that does it. In my testing, I fired up HiBy Music, which I haven't used in a while and it works beautifully with the Fosi DS2 / Tidal. Much faster at reading my internal storage of media files (~2600 FLACs in a single folder) than USBAPP and exclusive mode seems to work flawlessly with the Fosi DS2. I may just use this (and Neutron which also works well) instead of USBAPP if I can't resolve the issues.

 

[staticV3]

Thanks for the information! It is weird - I am continuing to troubleshoot this and can't see any setting that would cause these problems. I am going to re-install USBAPP and see if that does it. In my testing, I fired up HiBy Music, which I haven't used in a while and it works beautifully with the Fosi DS2 / Tidal. Much faster at reading my internal storage of media files (~2600 FLACs in a single folder) than USBAPP and exclusive mode seems to work flawlessly with the Fosi DS2. I may just use this (and Neutron which also works well) instead of USBAPP if I can't resolve the issues.

Have you tried sending an email to UAPP's developer?

He's usually super quick to respond and patch issues.

 

[Psinet]

I am a little surprised by the lack of interest in whether the balanced out of the DS2 is actually connected to a common ground - surely this is important for anyone wanting to use the balanced out as - a balanced out.

UPDATE: Fosi contacted me and said there is no stock, and asked if I am happy to wait, which of course I am.

No info on whether the balanced out has a common ground though.

 

[roladyzator]

I am a little surprised by the lack of interest in whether the balanced out of the DS2 is actually connected to a common ground - surely this is important for anyone wanting to use the balanced out as - a balanced out.

UPDATE: Fosi contacted me and said there is no stock, and asked if I am happy to wait, which of course I am.

No info on whether the balanced out has a common ground though.

I have a balanced cable for HE400E, Fosi Ds2 and a digital multimeter. How can I check this?

I presume I'd have to use resistance measurement mode to check for 0 Ohm from the sleeve of the 3.5mm trs connector that goes into the headphones to where ground should be, but where would that be? Some pin on the USB socket?

 

[staticV3]

I presume I'd have to use resistance measurement mode to check for 0 Ohm from the sleeve of the 3.5mm trs connector that goes into the headphones to where ground should be, but where would that be? Some pin on the USB socket?

The HE400se cable will not be connected to Pentaconn GND anywhere, so you'd have to purchase a Pentaconn DIY solder plug.

The 3.5mm TRS sleeve is connected to Cold instead.

 

[roladyzator]

So I can't simply add 3.5mm to 6.3mm stereo jack adapters at the end of the balanced headphone cable's one channel and connect that to active speaker's TRS input? Because I won't have the ground connection regardless of how Fosi is wired?

 

[roladyzator]

The HE400se cable will not be connected to Pentaconn GND anywhere, so you'd have to purchase a Pentaconn DIY solder plug.

The 3.5mm TRS sleeve is connected to Cold instead.

This is the cable that I've bought:

https://aliexpress.com/item/1005006785199421.html

The images in the description suggest that the pentaconn plug's sleeve is not connected to the ground, is that right?

 

[mc.god]

This is the cable that I've bought:

https://aliexpress.com/item/1005006785199421.html

The images in the description suggest that the pentaconn plug's sleeve is not connected to the ground, is that right?

Yes, that's right, headphones balanced cables don't have sleeve pin connected, for line connection you'll have to use something like this
https://it.aliexpress.com/item/1005005993835469.html
but ONLY if DS2 is confirmed to have common ground internally connected.

 

[staticV3]

So I can't simply add 3.5mm to 6.3mm stereo jack adapters at the end of the balanced headphone cable's one channel and connect that to active speaker's TRS input?

Correct.

Such a connection would lack grounding between DAC and Amp.

 

[Woai]

Wouldn’t this make more sense than the SMSL su1 if you just need an usb input DAC?