Fosi Audio DS2 Portable DAC & Amp Review

[melowman]

Can you recommend a cable to connect to an iPhone (13 mini) directly? I mean without going through an adapter, just a direct cable iPhone<->DS2. Thank you very much.

 

[Tassin]

You are looking for a USB-C to Lightning cable.

 

[melowman]

Sure, but one that is DAC compatible - and happy with high power draw - and of course reliable. Google has not been my friend that much so far, hence my question to direct users here.

 

[staticV3]

I can recommend this one: https://www.meenova.com/products/us...t-lt1-qudelix-5k-hiby-fc3-5-fd3-hidizs-s9-pro

 

[Somafunk]

Can you recommend a cable to connect to an iPhone (13 mini) directly? I mean without going through an adapter, just a direct cable iPhone<->DS2. Thank you very much.

You “may” find this DDHifi cable will work, it certainly worked with my iPhone XS and Chord Mojo 2, I also had luck with this FIIO cable but whilst it worked with the Mojo 2 it would not work with external Dacs that did not contain an internal battery due to power draw.

I wouldn’t want to say the above will 100% work as I don’t have a DS2 to check compatibility

You are looking for a USB-C to Lightning cable.

No, the cable needs to be a specific MFI certified OTG cable with audio pass through.

MFI = Made For IPhone

OTG = On The Go

 

[Viper780]

Why does it need to be OTG?

 

[staticV3]

Why does it need to be OTG?

Without OTG, the iPhone will refuse to supply power to the DS2.

 

[Viper780]

But shouldn't be the DAC on it's own be OTG capable?

 

[staticV3]

But shouldn't be the DAC on it's own be OTG capable?

An MFi accessory with Apple's MFi chip inside will work with any USB cable.

An accessory without MFi chip will require a USB cable with said chip.

I believe that's what's commonly referred to as a Lightning OTG cable.

Keep in mind that there are also Lighting MFi cables, which have another kind of MFi chip inside that tells the iPhone that the attached cable is safe for charging, but this will not signal to the iPhone that it should supply power to an external accessory.

A wonderful system brought to you by the geniuses at Apple RnD, alongside such master strokes as:

 

[MingRui]

A big thank you to Amir for the review.

The DS2 is one of our products as we make our entry into the high-performance DAC market. The DAC market is filled with many outstanding companies with which everyone is familiar. We will humbly learn from these companies as we continue to grow, and we hope to follow in their footsteps by bringing Fosi Audio’s unique touch to DACs for audiophiles worldwide. In addition to portable DACs, we’ll soon be introducing a desktop DAC as well.

To show our appreciation for the support from ASR members, we’re offering a special discount code for the DS2. You can use this code to get 20% off your DS2 purchase!
ASRDS220

link:
https://fosiaudio.com/products/fosi-audio-ds2-2024-dac-headphone-amplifier
https://www.amazon.com/dp/B0CTHN2QB3
https://www.amazon.de/dp/B0BJ66KJ2B
https://www.amazon.com.au/dp/B0BJ66KJ2B
https://www.ebay.com/itm/296311456320

Order placed on AliExpress

 

[melowman]

So here are some more results from a lazy Sunday afternoon.

I measured and wrote down the max values that the DS2 can provide at the edge of clipping - harmonics are about to rise but just do not. Excuse me to have done this first only for balanced (that is what I will mainly use):

600 Ohm: 4.0 V, +14.4 dBu, 118.2 dB THD+N, 27.5 mW

300 Ohm: 3.9 V, +14.1 dBu, 118.0 dB THD+N, 51.3 mW

50 Ohm: 2.9 V, +11.5 dBu, 112 dB THD+N, 170 mW

32 Ohm: 2.29 V, +9.4 dBu, 109 dB THD+N, 164 mW

16 Ohm: 1.2 V, +3.9 dBu, 105 dB THD+N, 92 mW

Note the discussion here about 510 mW output power - that is not there. With 1% THD I measured 2.6 V, +10.5 dBu aka 420 mW @ 32 Ohm still no match..

SNR: Base noise is a fixed -115.5 dBu (rms unweighted), plus the respective output level (for example 115.5+14.4= 129.9 dB, 115.5+9.4= 124.9 dB (all rms unweighted. dBA = +2.3 dB).

In my book pretty impressive so far. So let me first check @amirm 's dashboard to see if my unit can keep up:

View attachment 396912

Wow, it's even slightly better! Or my measurement setup was (when Amir measured the ASIO drivers were not known). Anyway, what bothered me most is that in this thread talk was CS would be cheating, THD/THD+N getting significantly worse when using lower impedance phones, with values of -80 and even -64 dB! Fortunately I can debunk this for the Fosi DS2, see here, a full sweep at 32 Ohm 2-channel load (in case you missed the above table where this was clearly visible already, with 16 Ohm still at -105 dB):

View attachment 396913

I mentioned that I had problems to do the sweep. Here is what is there and also what happens: enormous out-of-band junk, which at certain levels (around -25 dBFS) makes the special dual high performance input of the APx fail. The noise floor then is shown wrong, the notch filter fails as well, measurement values are all way off:

View attachment 396915

I was able to work around this by starting the sweep without the High Performance mode, then switching it on at around -10 dBFS. The result is valid and correct for the whole curve in the sweep picture.

Here is the same at full level (600 Ohm):

View attachment 396917

If I find the time I'll add some more.

Edit: I had a typo in my table and removed the statement about 510 mW @ 50 Ohm load.

If time allows, it would be great to have the same measurements for the 3.5mm output.

 

[jasonhanjk]

If time allows, it would be great to have the same measurements for the 3.5mm output.

Single ended results are worse off. Possible a hardware design issue copied from other companies that are using dual CS43131.

The CS43131 datasheet never recommend using 1 IC as left while another as right for single ended.

 

[Psinet]

Single ended results are worse off. Possible a hardware design issue copied from other companies that are using dual CS43131.

The CS43131 datasheet never recommend using 1 IC as left while another as right for single ended.

Balanced 4.4mm out to balanced TRS in on the miniDSP Flex balanced version sounds absolutely mint. I am using the USB-C splitter mentioned earlier to keep my phone charged at the same time it plays - I am actually using my phone as a mobile balanced source, at this dynamic range and low noise floor/distortion!?!?!?!?!?!?!

Insanity.

 

[melowman]

It’s been somewhat discussed before, but since the 4.4mm Sleeve is grounded, is there a benefit from using a 4.4mm to 3.5mm adapter like the iFi one, which has the L- and R- rings left unconnected and both Sleeves connected?
Will it even work? If yes shall we just expect 6dB less SINAD?

 

[MC_RME]

There is no benefit. You loose all the advantages of the balanced output (double voltage, quadruple power, lower THD), so get the same as using the DS2's 3.5mm output directly.

 

[jasonhanjk]

There is no benefit. You loose all the advantages of the balanced output (double voltage, quadruple power, lower THD), so get the same as using the DS2's 3.5mm output directly.

That really depends.
Balance output have a higher theoretical value of 1.414 times noise than single ended (3.5mm).
Balance also have higher risk of increase distortion than single ended with low impedance load (16 ohm).

For DS2 case, it's designed for balance. It's single ended design did not follow manufacturer's datasheet.
So I highly recommend to use the 4.4mm output.

 

[bricksie]

Just got my DS2 yesterday - no issues on my Android phone (OnePlus 7 Pro) nor on my old Windows 10 HP laptop. Both were just plug and play with no dropouts or other oddities. I tried both Foobar and PlexAmp on the laptop. I tried comparing the output directly from the DS2 vs using it as a preamp for a JDS Atom, and the DS2 seems to have more punch. This is the single-ended output only. More listening required...

 

[Olfa]

I'm using this on a pixel 8. Mixing between using the tidal app and USB audio pro app. Could someone please explain about the volume though and the best way to work it. Does the DS2 buttons work independently or can you also use the phones volume buttons. Or does the DS2 only let you use the buttons too go as high as whatever the phone volume has been set at. Thanks in advance as im a bit baffled between what apps best to use and what settings the volume best.

 

[roladyzator]

I'm using this on a pixel 8. Mixing between using the tidal app and USB audio pro app. Could someone please explain about the volume though and the best way to work it. Does the DS2 buttons work independently or can you also use the phones volume buttons. Or does the DS2 only let you use the buttons too go as high as whatever the phone volume has been set at. Thanks in advance as im a bit baffled between what apps best to use and what settings the volume best.

The Android and DS2 volume control are independent.
It's best to set the volume to the highest on the phone and then use the buttons

The device is using 24/192 output by default so lowering the volume in Android wouldn't necessary cause problems

 

[Olfa]

The Android and DS2 volume control are independent.
It's best to set the volume to the highest on the phone and then use the buttons

The device is using 24/192 output by default so lowering the volume in Android wouldn't necessary cause problems

That's great, thanks very much, totally makes sense.

I also saw there is a volume setting in the usb audio pro about volume and either hardware, software or none but I'm not sure what it really does.