Fosi Audio SK02 DAC & HP Amp Review

[amirm]

What would be the effect of the 4 ohm output impedance on HE400SE headphones (25 ohm impedance, very low but also entirely flat)?

No effect other than power loss which is reflected in my testing.

 

[mc.god]

What would be the effect of the 4 ohm output impedance on HE400SE headphones (25 ohm impedance, very low but also entirely flat)?

As for @solderdude measurements, absolutely nothing.

https://diyaudioheaven.wordpress.com/headphones/measurements/hifiman/he400se/

 

[MacClintock]

I'm using this Y cable for a USB device. On one side I have power, I use a very normal 5V power bank and on the other the phone.

Ok, that might be a nice solution if you are on the go. But this device is, at least in my eyes, too big and clumsy to be comfortably carried around. And if I am using it at my desk, why should I use a power bank if I can just have gear using a plug?

 

[Mikig]

Ok, that might be a nice solution if you are on the go. But this device is, at least in my eyes, too big and clumsy to be comfortably carried around. And if I am using it at my desk, why should I use a power bank if I can just have gear using a plug?

Don't take it as a scientific answer: in fact, maybe someone can be more explanatory. or even prove its ineffectiveness.
I have read from many places, even with serious comparisons, that DC power is very good for these devices.
It would improve the silence and the bass.
But I repeat, I can't give you a scientific answer, or measurements.
I tried it just out of curiosity, the cable cost a few euros and the power bank too...also the phone practically doesn't run out of battery!

 

[Daviede]

Yes, I think it's more convenient to bring a battery with SK02, but the current battery level is still too low. SK01 runs out of battery the next day at most, but it's enough for short trips.

 

[NeoZs99]

It's an entirely different device -- the SK01 is a preamp/EQ/headphone amp box (no DAC) that's battery powered (with only charging via its USB C receptacle), the SK02 is a DAC/headphone amp (no EQ) box that's powered via USB. The form factor is pretty much all the two devices have in common.

Thanks chief

 

[MacClintock]

Don't take it as a scientific answer: in fact, maybe someone can be more explanatory. or even prove its ineffectiveness.
I have read from many places, even with serious comparisons, that DC power is very good for these devices.
It would improve the silence and the bass.
But I repeat, I can't give you a scientific answer, or measurements.
I tried it just out of curiosity, the cable cost a few euros and the power bank too...also the phone practically doesn't run out of battery!

Please, no. You may consult the measurements and tests of a bunch of power conditioners and the like here on ASR. There is simply no evidence for any effect of the source power to sound.

 

[solderdude]

@Fosi Audio

specs say 1100mW in 32 ohm... why not specify it as others do... 2x550mW in 32ohm (balanced)
of course 1100mW looks more impressive on a spec sheet.

The Ultra-Low Noise spec is funny.. it states it in micro Farad instead on micro Volt (so not μF but μV)

also funny to read sound is masterfully restored instead of reproduced

 

[mc.god]

also funny to read sound is masterfully restored instead of reproduced

I see this everywhere on marketing of chinese audio products, maybe a common glitch of automatic translators CHN-EN

 

[Doodski]

I see this everywhere on marketing of chinese audio products, maybe a common glitch of automatic translators CHN-EN

Hehe... If you think that is amusing the Japenglish would amaze and entertain you as you use some of the best technical literature and schematics ever made... There is such a contrast to the funny terminology Japenglish used and the sophistication of the awesome service literature from Japan.

 

[KSTR]

Voted "not terrible". It's an OK product but I don't like the design with that overhanging front plate.

The ESS hump is more of a real issue, and @amirm sure has some point in that ESS should offer the info required to avoid it. But it's a business and they do whatever they see fit to support their business model which was questionable from the very beginning of the company. Implementers, by now anyway, should know what's needed to get good measurements from an ES9038q2m.

 

[Sir Sanders Zingmore]

Local reviewer here ran a noise signal through the little DAC and got worrisome results. I don't know how to properly interpret it, maybe it is due to the rising THD up the high frequencies shown here as well?

Spoiler

View attachment 356027

Other than that, the high gain power max was 40% behind spec, but should be fine for class and price. In this sense, I must admit, this device's feature set astonishes me for the price. Not mentioned here in the review is it's DDC capability: it's aux out doubles as spdif out. Maybe you could measure it too @amirm ?

Not sure what we are looking at here - I can't read what the axes are - but it looks pretty bad.
I've scanned the thread to see if anyone else has commented and I don't see anything.
Do you have any more info or can anyone else shed some light on what this is showing?

 

[mc.god]

Hehe... If you think that is amusing the Japenglish would amaze and entertain you as you use some of the best technical literature and schematics ever made... There is such a contrast to the funny terminology Japenglish used and the sophistication of the awesome service literature from Japan.

I know it well, as a former anime fansubber I encountered many funny examples back in the days.

 

[Fosi Audio]

@Fosi Audio

specs say 1100mW in 32 ohm... why not specify it as others do... 2x550mW in 32ohm (balanced)
of course 1100mW looks more impressive on a spec sheet.

The Ultra-Low Noise spec is funny.. it states it in micro Farad instead on micro Volt (so not μF but μV)

also funny to read sound is masterfully restored instead of reproduced

Thank you for your corrections. We'll revise them shortly.

 

[Leiker535]

Not sure what we are looking at here - I can't read what the axes are - but it looks pretty bad.
I've scanned the thread to see if anyone else has commented and I don't see anything.
Do you have any more info or can anyone else shed some light on what this is showing?

Here's a better picture, y axis is SPL (10 dB delta) and x axis is frequency up till 22khz.

Spoiler

It comes from this video, where the reviewer measures FR using a certain noise (not sure which, brown, white or pink). His other FR measurement is fine, with minor deviations probably due to the rudimentary analyzer. He basically says the problematic one comes probably from a problem with the DAC's filtering at the output. Here's the other measurement and video:

Spoiler

 

[pseudoid]

@Fosi Audio
specs say 1100mW in 32 ohm... why not specify it as others do... 2x550mW in 32ohm (balanced)
of course 1100mW looks more impressive on a spec sheet.
The Ultra-Low Noise spec is funny.. it states it in micro Farad instead on micro Volt (so not μF but μV)
also funny to read sound is masterfully restored instead of reproduced

Your valid post may have just caused a copy-editor's job.
Can someone please re-translate what a "Ring Cow" is and how it came about?

 

[catch22]

Haha

Your valid post may have just caused a copy-editor's job.
Can someone please re-translate what a "Ring Cow" is and how it came about?
View attachment 356707

also funny to read sound is masterfully restored instead of reproduced

I am not a native English speaker myself, but I always wonder why some companies don't get a a native speaker to proof-read. It's not a million pages, just a dozen per product. Won't cost a fortune. Even a free product would do Would look much more proferssional without a Ring Cow

 

[Bruno]

Overall results suggest this to be an honest piece of hardware sold at an interesting price. User Interface wise it looks like a well designed device. Performance wise I was surprised to see it lagging behind the Hidizs DH80S. Slightly better performance, it's portable and battery powered, all for a few bucks more.

 

[morpheusX]

I have a Sennheiser momentum 2, which has an integrated microphone.
Would the Microphone still work when connected to this amp/dac?

 

[Kimbrough Xu]

I have a Sennheiser momentum 2, which has an integrated microphone.
Would the Microphone still work when connected to this amp/dac?

I dont think so, the headphone can work, but not the microphone. Fosi has a K5 PRO which can support microphone.