Fiio K11 R2R DAC/HPAMP measurements

[swa2023]

This is a simple measurement of Fiio K11 R2R DAC and headphone amplifie.
Some setup, 200kohm input impedance, 48khz sample rate, 20khz bandwidth.

Balance ouput

Dynamic range, No weighting

50mV SNR, 32ohm load, No weighting

Linearity, 1khz sine, elliptic filter low and high pass from 900hz to 1100hz

IMD SMPTE

32 multitone, 256k FFT

THD+N frequency sweep

Frequency response

Max output, 32ohm and 300ohm

As you see, I tested this last year, but forgot to post.LOL

Conclusion, too many harmonics.

 

[JSmith]

Pretty spot on in comparison to their spec's page 72.04 dB SINAD, or 0.025% THD+N;

Guangzhou FiiO Electronics Technology Co., Ltd.-K11 R2R_parameters

Guangzhou FiiO Electronics Technology Co., Ltd.

fiio.com

Oh that's nasty.

Thanks for posting your testing results.


JSmith

 

[AnalogSteph]

Not great indeed. Dynamic range is fundamentally decent, but -72 dB THD+N at 0 dBFS would make converters from the digital dark ages around 1980 blush. (I just added some to the list...)

 

[vAudioArchitect]

may i ask a question please.
was this done in OS or NOS modes?

ta

 

[BGMeek]

Well good (it's not just my ears then). I got one this morning via Amazon and have been alternating listening to the K11 R2R and a Fosi Audio SK02 that I was thinking I would return if the K11 R2R had lived up to all the hype.

Well, I don't care if the K11 R2R sounds more "organic" or nostalgic whatever, it's just missing/masking too many details I'd rather hear. The Fosi SK02 is sounding much better! More... complete.

 

[vAudioArchitect]

Well good (it's not just my ears then). I got one this morning via Amazon and have been alternating listening to the K11 R2R and a Fosi Audio SK02 that I was thinking I would return if the K11 R2R had lived up to all the hype.

Well, I don't care if the K11 R2R sounds more "organic" or nostalgic whatever, it's just missing/masking too many details I'd rather hear. The Fosi SK02 is sounding much better! More... complete.

May I ask what’s missing ?

 

[BGMeek]

May I ask what’s missing ?

Clarity of details across the spectrum, really. I'm finding treble and midrange bits that are overlooked or not fully identifiable with the FiiO, but are then revealed with the Fosi. For example, I just plugged my HD 6XX headphones' balanced cable into the FiiO K11 R2R again for a fresh morning listen while answering your question, and Dire Straights' Follow Me Home came on - with the beach sounds and bongos in the intro - when I switched back to the Fosi for comparison I recognized the higher-tone bamboo percussion instruments for what they actually are, while on the FiiO R2R they were merely well-timed sounds/beats in the song that failed to remind me of a bamboo wind chime.

Now, with the FiiO, things do 'sound good', I enjoy good music playing through it. But switching back to the Fosi always reveals a greater level of detail that I don't want dropped. I used to mess around in Photoshop with photos scanned from film (yeah, I'm old). A high-res scan would reveal film grain and dust, so a Gaussian blur would be applied to smooth out such noise - the overall pic looks a bit better, but it still chaffs to lose the clarity of detail that also revealed unwanted flaws in the image. It seems K11 R2R is a bit 'too blurred' for me .

FWIW, I'm listening to these two dac/headphone amps with various open-back headphones, usually a Sony MDR-MV1, using balanced connections. Just switching that 4.4mm plug between them and replaying occassional bits for the A/B compare. FWIW, I'm a lifelong music lover but new to the headphone hobby this year and I'm not fluent, nor particularly interested, in audiophile-speak. I started listening to Rolling Stone Magazine's Top 500 Albums list using Apple Music in January to replace my anger-inducing news junkie habit, and I've been collecting headphones to plug into my M2 MacBook Air or a mobile Qudelix 5K BT DAC/Amp (I'm preferring it to the K11 R2R as well).

I'm now looking for a desktop DAC & headphone amp with a proper volume knob that'll also get the most out of all the 'Hi-Res' lossless audio that I'm encountering... I know that my sixty-year-old-ears can't hear anything close to 20kHz, but I do appreciate the mathematics of higher sampling rates with enough slack to reduce quantization errors and such in the digital domain - I can believe that the ongoing "Hi-Res" audio [re]mastering will occasionally result in better sound across my audible frequency range.

 

[JIW]

Clarity of details across the spectrum, really. I'm finding treble and midrange bits that are overlooked or not fully identifiable with the FiiO, but are then revealed with the Fosi. For example, I just plugged my HD 6XX headphones' balanced cable into the FiiO K11 R2R again for a fresh morning listen while answering your question, and Dire Straights' Follow Me Home came on - with the beach sounds and bongos in the intro - when I switched back to the Fosi for comparison I recognized the higher-tone bamboo percussion instruments for what they actually are, while on the FiiO R2R they were merely well-timed sounds/beats in the song that failed to remind me of a bamboo wind chime.

Now, with the FiiO, things do 'sound good', I enjoy good music playing through it. But switching back to the Fosi always reveals a greater level of detail that I don't want dropped. I used to mess around in Photoshop with photos scanned from film (yeah, I'm old). A high-res scan would reveal film grain and dust, so a Gaussian blur would be applied to smooth out such noise - the overall pic looks a bit better, but it still chaffs to lose the clarity of detail that also revealed unwanted flaws in the image. It seems K11 R2R is a bit 'too blurred' for me .

FWIW, I'm listening to these two dac/headphone amps with various open-back headphones, usually a Sony MDR-MV1, using balanced connections. Just switching that 4.4mm plug between them and replaying occassional bits for the A/B compare. FWIW, I'm a lifelong music lover but new to the headphone hobby this year and I'm not fluent, nor particularly interested, in audiophile-speak. I started listening to Rolling Stone Magazine's Top 500 Albums list using Apple Music in January to replace my anger-inducing news junkie habit, and I've been collecting headphones to plug into my M2 MacBook Air or a mobile Qudelix 5K BT DAC/Amp (I'm preferring it to the K11 R2R as well).

I'm now looking for a desktop DAC & headphone amp with a proper volume knob that'll also get the most out of all the 'Hi-Res' lossless audio that I'm encountering... I know that my sixty-year-old-ears can't hear anything close to 20kHz, but I do appreciate the mathematics of higher sampling rates with enough slack to reduce quantization errors and such in the digital domain - I can believe that the ongoing "Hi-Res" audio [re]mastering will occasionally result in better sound across my audible frequency range.

What do you mean by volume knob? An analog volume control or is a digital control with volume level indication also fine? Many DAC/HPAs use digital volume control. However, the Topping DX1 seems to use a potentiometer.

 

[BGMeek]

What do you mean by volume knob? An analog volume control or is a digital control with volume level indication also fine? Many DAC/HPAs use digital volume control. However, the Topping DX1 seems to use a potentiometer.

Hi.

I'm just talking about a proper dial for the DAC/Amp's UI (for the [likely] digital control of volume). The Fosi SK02 I'm now keeping fits the bill as it has a nice big dial on top, mounted horizontally, that also has a pause/resume function when pressed. I'm liking it more since I heard the FiiO K11 R2R .

I see this Fosi SK02 was reviewed here not too long ago.

FWIW, I returned the FiiO K11 R2R.

 

[JIW]

Hi.

I'm just talking about a proper dial for the DAC/Amp's UI (for the [likely] digital control of volume). The Fosi SK02 I'm now keeping fits the bill as it has a nice big dial on top, mounted horizontally, that also has a pause/resume function when pressed. I'm liking it more since I heard the FiiO K11 R2R .
View attachment 432257
I see this Fosi SK02 was reviewed here not too long ago.

FWIW, I returned the FiiO K11 R2R.

Amir reviewed it as well. Not state of the art but should be decent enough. Output impedance is around 3.1 Ohm for the unbalanced so 6.2 Ohms for the balanced output (calculation below). That may be an appreciable area of improvement with low impedance headphones.

Calculation of output impedance.
Power at 300 Ohm unbalanced is 26.53 mW and power at 33 Ohm unbalanced is 205.6 mW. Both are not clipping and so voltage is limited by gain alone. For a given load, the voltage across it is
V_L = Z_L/(Z_L+Z_O)*V
where Z_L is the load impedance and Z_O is the output impedance. Thus, the ratio of voltages for different loads is
V_L1/V_L2 = (Z_L1/(Z_L1+Z_O))/(Z_L2/(Z_L2+Z_O)) = Z_L1/Z_L2*(Z_L2+Z_O)/(Z_L1+Z_O).
Thus,
(Z_L1+Z_O)V_L1/V_L2 = Z_L1/Z_L2*(Z_L2+Z_O)
and thus
(Z_L1/Z_L2 - V_L1/V_L2)*Z_O = V_L1/V_L2*Z_L1-Z_L1/Z_L2*Z_L2 = (V_L1/V_L2-1)*Z_L1.
Thus, the output impedance is
Z_O = (V_L1/V_L2-1)/(Z_L1/Z_L2 - V_L1/V_L2)*Z_L1.
Since P = V^2/Z, V = (P*Z)^.5, using the measurements, the output impedance of the unbalanced output of the SK02 is
Z_O = (((26.53/1000*300)^.5/(205.6/1000*33)^.5)-1)/(300/33 - ((26.53/1000*300)^.5/(205.6/1000*33)^.5))*300 = 3.1125 Ohm.

 

[BGMeek]

Amir reviewed it as well. Not state of the art but should be decent enough. Output impedance is around 3.1 Ohm for the unbalanced so 6.2 Ohms for the balanced output (calculation below). That may be an appreciable area of improvement with low impedance headphones.

Thanks. Yes, I saw Amir's review too after my post - makes sort of a nice affirmation of my purchase .

I'm in early-stage learning about this stuff, so your observation prompted me to search 'output impedance of headphone amps'. I gather that an amp's output impedance shoud be much lower than the headphones' impedance (AI search reports 1/8 is an OK rule-of-thumb). My Sony MDR-MV1 have an impedance of only 24 Ohms (sensitivity: 100 dB/mW), and while they sound great with the Fosi SK02 using a balanced connection, perhaps I should try using an SE connection instead to better meet that rule-of-thumb? What would I be hearing if my balanced damping factor were too low?

Another factor that has me curious is Fosi's stated frequency response for the SK02 - it's narrower than I expected at 20Hz-20kHz. Aren't most marketing teams selling 'Hi-Res' Amps with numbers around 10Hz to 45kHz? I know my ears almost certainly can't hear anything outside of 20Hz-20kHz at any volume I'm gonna choose, but what's up with that?

Calculation of output impedance.
Power at 300 Ohm unbalanced is 26.53 mW and power at 33 Ohm unbalanced is 205.6 mW. Both are not clipping and so voltage is limited by gain alone. For a given load, the voltage across it is
V_L = Z_L/(Z_L+Z_O)*V
where Z_L is the load impedance and Z_O is the output impedance. Thus, the ratio of voltages for different loads is
V_L1/V_L2 = (Z_L1/(Z_L1+Z_O))/(Z_L2/(Z_L2+Z_O)) = Z_L1/Z_L2*(Z_L2+Z_O)/(Z_L1+Z_O).
Thus,
(Z_L1+Z_O)V_L1/V_L2 = Z_L1/Z_L2*(Z_L2+Z_O)
and thus
(Z_L1/Z_L2 - V_L1/V_L2)*Z_O = V_L1/V_L2*Z_L1-Z_L1/Z_L2*Z_L2 = (V_L1/V_L2-1)*Z_L1.
Thus, the output impedance is
Z_O = (V_L1/V_L2-1)/(Z_L1/Z_L2 - V_L1/V_L2)*Z_L1.
Since P = V^2/Z, V = (P*Z)^.5, using the measurements, the output impedance of the unbalanced output of the SK02 is
Z_O = (((26.53/1000*300)^.5/(205.6/1000*33)^.5)-1)/(300/33 - ((26.53/1000*300)^.5/(205.6/1000*33)^.5))*300 = 3.1125 Ohm.

Good stuff! Both of my parents and many dear friends have masters and doctorates in mathematics... while I can appreciate the concepts, I'm not fluent.

 

[JIW]

Thanks. Yes, I saw Amir's review too after my post - makes sort of a nice affirmation of my purchase .

I'm in early-stage learning about this stuff, so your observation prompted me to search 'output impedance of headphone amps'. I gather that an amp's output impedance shoud be much lower than the headphones' impedance (AI search reports 1/8 is an OK rule-of-thumb). My Sony MDR-MV1 have an impedance of only 24 Ohms (sensitivity: 100 dB/mW), and while they sound great with the Fosi SK02 using a balanced connection, perhaps I should try using an SE connection instead to better meet that rule-of-thumb? What would I be hearing if my balanced damping factor were too low?

Another factor that has me curious is Fosi's stated frequency response for the SK02 - it's narrower than I expected at 20Hz-20kHz. Aren't most marketing teams selling 'Hi-Res' Amps with numbers around 10Hz to 45kHz? I know my ears almost certainly can't hear anything outside of 20Hz-20kHz at any volume I'm gonna choose, but what's up with that?


Good stuff! Both of my parents and many dear friends have masters and doctorates in mathematics... while I can appreciate the concepts, I'm not fluent.

High output impedance causes a loss of level at the headphone which depends on the impedance of the headphone. If headphone impedance varies, it frequency response is modified. The impedance of the MDR-MV1 is quite varied with a broad peak at 70 Hz of 35 Ohm and minimum of 26 Ohm. With the SK02 unbalanced, that would be a 0.2421 dB boost and balanced the boost would be 0.4425 dB. That should be fairly subtle.

Source.

Also, high output impedance lowers the electrical damping of the headphone drivers' resonances leading to poorer impulse response.

You can read this to get an idea about output impedance.

20-20kHz is at +-0.02 dB so should be fine.

 

[BGMeek]

High output impedance causes a loss of level at the headphone which depends on the impedance of the headphone. If headphone impedance varies, it frequency response is modified. The impedance of the MDR-MV1 is quite varied with a broad peak at 70 Hz of 35 Ohm and minimum of 26 Ohm. With the SK02 unbalanced, that would be a 0.2421 dB boost and balanced the boost would be 0.4425 dB. That should be fairly subtle.
View attachment 432677
Source.

Also, high output impedance lowers the electrical damping of the headphone drivers' resonances leading to poorer impulse response.

You can read this to get an idea about output impedance.

20-20kHz is at +-0.02 dB so should be fine.

A somewhat belated 'Thank you!' for running those calcs on my setup. Thanks also for the pointer to NwAvGuy's thorough post on 'Headphone & Amp Impedance'.

As you say, any impact from the SK02's balanced output impedance on the Sony MDR-MV1s is indeed 'subtle' - it's nothing I can hear anyway. This is good, as I do prefer the balanced connection for the SK02's additional headroom in that mode.

 

[totti1965]

And as always: For a true subjectivist - even 72.2 dB SINAD (50 dB below SOTA!) is quite more than enough - because of the „beautiful bass-texture“

 

[Guddu]

And as always: For a true subjectivist - even 72.2 dB SINAD (50 dB below SOTA!) is quite more than enough - because of the „beautiful bass-texture“

Good to see ASR audience following expensive golden ear reviewers on youtube...

/s

 

[Music1969]

This is a simple measurement of Fiio K11 R2R DAC and headphone amplifie.
Some setup, 200kohm input impedance, 48khz sample rate, 20khz bandwidth.

Balance ouput
View attachment 422934

Dynamic range, No weighting
View attachment 422935

50mV SNR, 32ohm load, No weighting
View attachment 422936

Linearity, 1khz sine, elliptic filter low and high pass from 900hz to 1100hz
View attachment 422937

IMD SMPTE
View attachment 422938

32 multitone, 256k FFT
View attachment 422939

THD+N frequency sweep
View attachment 422940

Frequency response
View attachment 422941

Max output, 32ohm and 300ohm
View attachment 422944
View attachment 422945

As you see, I tested this last year, but forgot to post.LOL

Conclusion, too many harmonics.

Hi do you still have the DAC?

Can you use something like Roon to upsample to and output 16-bit 353kHz?

With high quality filtering and 16-bit output (linearity is clearly not good enough for 24bit..) the output should be much cleaner

 

[Pareto Pragmatic]

Well, I don't care if the K11 R2R sounds more "organic" or nostalgic whatever, it's just missing/masking too many details I'd rather hear.

95% of the time I go for detail. But I see the appeal of less. I'm not buying anything to get there, I can just run my vintage speakers, or use my low level AVR, or sit way too far away from the speakers and let my room blur things.

Knowing there are problems means I don't worry about them, knowing there is less detail I don't look for it. I tend to listen to the music as a whole, not focus on any one part. So that's what I think might be part of the attraction to people, that lack of detail lets them get into the music more. Which is fine.

Plus it reminds me of how far my system has come over the past few years. Which helps me NOT be dissatisfied with what I have now, which is worth a lot in terms of gear chasing. That's worth an occasional session or two, for sure. Coming back to my main set up after that usually makes me smile wide, that's for sure.

 

[vAudioArchitect]

Hi do you still have the DAC?

Can you use something like Roon to upsample to and output 16-bit 353kHz?

With high quality filtering and 16-bit output (linearity is clearly not good enough for 24bit..) the output should be much cleaner

i have it connected to the SR11 Roon end point over USB oversampling up to 384Khz if i'm not mistaken via Roon, sounds good and clean, i personally cant hear any noise in the chain, the oversampling does make it sound a little more wide and airy maybe that's the cleaner sound of oversampling i'm hearing.

not a big difference but its distinguishable when switching back and forth.

I just leave it on all the time, very enjoyable.

It would be interesting to get some real testing done to see the oversampling effect plotted in a graph vs NOS.

Just curious more than anything.

 

[Music1969]

i have it connected to the SR11 Roon end point over USB oversampling up to 384Khz if i'm not mistaken via Roon, sounds good and clean, i personally cant hear any noise in the chain, the oversampling does make it sound a little more wide and airy maybe that's the cleaner sound of oversampling i'm hearing.

not a big difference but its distinguishable when switching back and forth.

I just leave it on all the time, very enjoyable.

It would be interesting to get some real testing done to see the oversampling effect plotted in a graph vs NOS.

Just curious more than anything.

best to set 16bit

 

[BGMeek]

What do you mean by volume knob? An analog volume control or is a digital control with volume level indication also fine? Many DAC/HPAs use digital volume control. However, the Topping DX1 seems to use a potentiometer.

Hi there - a bit of follow-up after my last response about this esoterically-interesting digital vs. analog volume dial question...

I recently sprung for an iFi Zen DAC 2 and its enhanced-headphone-amp-cousin, the Zen CAN Signature (a 2023 generic version). Both of these units sport an analog volume knob, and I'm really enjoying the sound and the power of this balanced combo.

More to the point, I find I enjoy the smooth action of the Zen CAN Sig's pot-connected volume knob, and its predictable positioning, over the Fosi SK02's infinitely-rotatable digital knob for volume control. But - the horizontal mount of the SK02's larger volume knob is just very cool, and its additional digital functions when pressed: play/pause for one press; mute/unmute for double-press, are really handy features given the placement of the big knob/button.