Fosi DS1 Portable DAC & Headphone Amp Review

[amirm]

This is a review and detailed measurements of the Fosi Audio DS1 portable usb-c DAC and balanced headphone amplifier. It is on kind loan from a member and is on sale for US $68.

The look is distinctive. Sharp edges give it style but perhaps would be a bit rough in worn in pants pocket. Most important features are nice volume control buttons and inclusion of "balanced" headphone output. I focused my testing on that.

Fosi DS1 Measurements
As usual we start with our dashboard at max volume:

Nice to see 4 volts out! This means we will have plenty of power for high impedance headphones. Combination of noise and distortion is very good for the class and would have been better if Ch2 had the same performance as Ch1:

Noise performance is excellent at full power, but average for class at 50 mv:

Multitone performance is excellent:

As is jitter:

As predicted, power into 300 ohm is quite good:

Notice how it beats its newer, DS2 brother. Same is true for 32 ohm load:

Conclusions
The DS1 is very well designed and quite powerful, able to drive a lot of headphones to good volume. It loses slightly to the DS2 variant in noise and distortion but makes up for it in available power.

I am happy to recommend the Fosi DS1 headphone amplifier and DAC.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[amirm]

Reserved for @AdamG to kindly post the specs.

Manufacturer Specifications:

Link to product information:

Fosi Audio DS1 DAC Amp | Hi-Res USB | Headphone Outputs

Elevate your music experience with Fosi Audio DS1 headphone amplifier. Enjoy hi-res sound from your phone, tablets, PCs, gaming consoles, and more.

fosiaudio.com

 

[phoenixsong]

Interesting how they follow the similar naming/numbering scheme despite having a different focus on low noise/distortion vs power. I wish it were different for as it is, it is easy to immediately assume the DS2 superior without going into more specs and reviews, which can be misleading

 

[staticV3]

As predicted, power into 300 ohm is quite good:
[...]
Notice how it beats its newer, DS2 brother.

Fairly certainly only because you used the driver translation layer for your DS2 measurements which caused increased noise and distortion.

Without that, you'd see 4.1^2/300=56mW out of the DS2 without clipping.

Easy to confirm without messing with drivers by repeating the default 1kHz 0dBFS test, but reducing the load impedance from 600 to 300Ω:

 

[amirm]

Fairly certainly only because you used the driver translation layer for your DS2 measurements which caused increased noise and distortion.

I don't see how that issue impacts power rating.

 

[mc.god]

Thank you for the review, always been curious about this dongle.
It is older than the DS2, or at least i remember seeing it on the market much earlier, and unlike DS2 it uses an ESS ES9038Q2M dac, so it has to implement separate op-amps for output stage that i don't know (but i bet on Ricore RT6863D), giving a bit more power than the integrated output stage of the CS43131.
The 50mV noise is honestly disappointing.

 

[Power Pop 23]

@amirm,

thank you for the review,

Your September 2024 review of the Fosi Audio 'DS2' dongle found it to have enough output power (172 milliwatts into 32 ohms) to make it 'perfectly usable' with the Dan Clark Audio 'E3' headphone. Barring a listening test, is it likely the more powerful 'DS1' dongle can be even more 'perfectly usable' with the more efficient Dan Clark Audio 'Noire X' headphone ?

 

[staticV3]

I don't see how that issue impacts power rating.

It does, but after closer examination not in the way I initially thought. My apologies!

It looks like the DS2 does indeed clip at 0dBFS 300Ω (=56mW), as shown in your sweep and indicated by @MC_RME here.

It then regains clean playback at about -0.3dBFS (≈52mW).

But your DS2 sweep placed the first step after clipping at -1.2dBFS (≈43mW), so skipped over the exact clipping point, slightly underestimating the amount of clean power.

 

[staticV3]

Your September 2024 review of the Fosi Audio 'DS2' dongle found it to have enough output power (172 milliwatts into 32 ohms) to make it 'perfectly usable' with the Dan Clark Audio 'E3' headphone. Barring a listening test, is it likely the more powerful 'DS1' dongle can be even more 'perfectly usable' with the more efficient Dan Clark Audio 'Noire X' headphone ?

Not only is the Noire X about 4dB less sensitive than the E3 (=25% quieter at the same Amp volume), but it also has way lower impedance (13Ω down from 27Ω on the E3), which means that the Amp will clip at a lower volume setting when driving it instead of the E3.

That is not to say that the DS1 is incapable of giving you satisfying playback with the Noire X. That depends on many factors unique to you alone.

But it will not play the Noire X as loud as it could the E3.

 

[CedarX]

Per the manufacturer description, it appears there is a low/high gain (?) mode selection—although it doesn’t say how to select it:

Could this affect the measurements results?

 

[Martin]

Also mine. Fosi seems do most everything right. I love the power this thing has. It seems a good match to the 7Hz Timeless.

Martin

 

[Martin]

Per the manufacturer description, it appears there is a low/high gain (?) mode selection—although it doesn’t say how to select it:
View attachment 439664

Could this affect the measurements results?

A simultaneous push of the up and down volume buttons toggles between high and low gain.

Martin

 

[MC_RME]

But does it have the same volume ramp up issue as the DS2?

 

[jkim]

A simultaneous push of the up and down volume buttons toggles between high and low gain.

Martin

Then, may Amir remeasure its 50 mV SNR in the Low Level mode?

 

[Martin]

But does it have the same volume ramp up issue as the DS2?

I have not noted the issue with my iPhone. I have not used it with Windows or Android.

Martin

 

[Multicore]

inclusion of "balanced" headphone output. I focused my testing on that.

What does this mean for those of use who have no phones with "balanced" connection? Seek a different product?

 

[mc.god]

What does this mean for those of use who have no phones with "balanced" connection? Seek a different product?

I suppose he simply didn't measure SE connection for convenience.

 

[Multicore]

I suppose he simply didn't measures SE connection for convenience.

I mean technically. A "balanced" phones connection has four conductors, iiuc, so how do we use that with our devices that have only three? Does it work? I really don't know. And what difference in performance should be expected, if any.

 

[mc.god]

I mean technically. A "balanced" phones connection has four conductors, iiuc, so how do we use that with our devices that have only three? Does it work? I really don't know. And what difference in performance should be expected, if any.

If you headphone has balanced cable (or supports it by changing it) with 4 pin TRRS jack you connect it to the "balanced" 4.4 mm output of the DS1, if it has SE TRS jack you connect it to the SE 3.5 mm output of the DS1 (if it is what you are asking).
No audible difference in performance, only more power.

 

[HalSF]

I’ve been enjoying the DS2 for a couple of months now, but of course would like significantly more power for challenging headphones. I’m just not sure if the DS1 is more powerful enough to justify a switch from the later model given how happy I’ve been in general.