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Review and Measurements of Fiio K5 Pro

prakosza

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#21
Hmm... I'm kinda a noob so I hope I won't sound stupid asking that but what does it mean when you say that at 1 volt sinbad is better? I can understand that means it plays more quite than on 2 volts but what it means it practice? Oh and would it be possible (if it even makes any seans to check sinbad on usb -> hp)?
 

daftcombo

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#22
Hmm... I'm kinda a noob so I hope I won't sound stupid asking that but what does it mean when you say that at 1 volt sinbad is better? I can understand that means it plays more quite than on 2 volts but what it means it practice? Oh and would it be possible (if it even makes any seans to check sinbad on usb -> hp)?
"Sinbad" is better means that THD+Noise is lower. If you play your tunes at -6dB max (via a hard limiter in Foobar2000 for instance, of setting Windows volume a bit under 100), you will have less THD+N hence better sound. Not that you would hear a difference though.
 
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amirm

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#23
Hmm... I'm kinda a noob so I hope I won't sound stupid asking that but what does it mean when you say that at 1 volt sinbad is better? I can understand that means it plays more quite than on 2 volts but what it means it practice? Oh and would it be possible (if it even makes any seans to check sinbad on usb -> hp)?
As long as you don't play as loud, you would get the lower distortion that lower output represents. For standardization, I use 2 volt but that would be louder than you would normally use here.
 

prakosza

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#24
"Sinbad" is better means that THD+Noise is lower. If you play your tunes at -6dB max (via a hard limiter in Foobar2000 for instance, of setting Windows volume a bit under 100), you will have less THD+N hence better sound. Not that you would hear a difference though.
As long as you don't play as loud, you would get the lower distortion that lower output represents. For standardization, I use 2 volt but that would be louder than you would normally use here.
Thank you for your answers :) Does 2v output means that it's always on the same loudness level on every device or is there any other parameter of electricity that determines loudness other than voltage?

Edit:
To clarify if 2v will always mean the same level of loudness coming from device devices into for example the same pair of headphones.
 

zermak

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#25
@prakosza
2 volts (RMS) is the output you will have when you play a sine wave (or audio file or anything else) that reaches 0dBFS so it means in reality it will not happen frequently if you use properly mastered audio files/music. Maybe some very compressed songs, cause of the DR war, reach it more frequently.

Side note. When you will play it through an amplifier (mainly for headphone) you will surely lower the output voltage before it reaches the amp stage because of the nature of amp (or we would name it differently) and its gain.

I am not an expert and I am sure someone else will explain it more technically.
 
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#26
Hi amir, for DAC/amp combo units wouldn't it be more appropriate to measure usb->headphone out since this is their main use? In this case isn't there a possibility that it'll measure worse than if you added the individual DAC and amp measurments.
 

mkawa

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#27
he did that. the headphone out graphs in the OP are from usb to HP out. the second set of measurements further along in the thread are from line in to headphone out. the measurements don't change much because the dac has been designed to output signal that just barely out-resolves the HP amp. adding more resolution via the line in doesn't really help because the HP amp is the distortion bottleneck

this is also why it's 149$ prime shipping on amazon right now. for that you get a dac, HP amp and 15v psu capable of putting 1W into a pair of headphones.
 

amirm

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#28
Does 2v output means that it's always on the same loudness level on every device or is there any other parameter of electricity that determines loudness other than voltage?
It will play at the same volume on every device if they all have 2 volt output.
 

amirm

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#29
Hi amir, for DAC/amp combo units wouldn't it be more appropriate to measure usb->headphone out since this is their main use?
That is exactly what the measurements are. If there is a DAC in there, I always use USB unless I say otherwise.
 

amirm

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#30
Edit:
To clarify if 2v will always mean the same level of loudness coming from device devices into for example the same pair of headphones.
This is not correct for DACs. You would have an amplifier after them and that would determine how loud they get.
 

mkawa

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#33
oh, one correction, i think. the device uses an NJW1195A relay based single chip volume control. njw11985a is a resistance ladder analog domain attenuator, not a digital domain volume control (the ak4493's digital volume control is lossy).
 

scooter

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#34
It is the same as digital in since the DAC is not the limiting factor:

View attachment 34374

I did not try to mess with it and reduce the impact of the mains leakage so ignore that part.
As mentioned in the review, line out is not constant 2V. But why does it compromise DAC SINAD when it should be isolated from amplified headphone out?
Line out is supposed to be direct output from DAC before reaching amplifier section circuits, or am I wrong?
I guess optical in - line out would have the same measurement as usb in - line out?
 

Vovgan

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#35
Hi amir, for DAC/amp combo units wouldn't it be more appropriate to measure usb->headphone out since this is their main use?
That is exactly what the measurements are. If there is a DAC in there, I always use USB unless I say otherwise.
I think both @irrationophile and I understood your measurements in the same way. In the main review under "DAC measurements" you mentioned that it was for digital (USB?) in -> line out. “Line out” is not the same as headphone out - right? This Fiio has "line out" outputs on its rear panel.
After that you posted additional measurements for analog “line in -> headphone out”. Each of these two separate measurements produced almost identical SINAD of around 82. And these are the only two SINAD numbers that we see. But these are two separate sub-systems - DAC and amplification - so is it correct to assume that their combined SINAD (“USB in -> headphone out”) is around 76?

Or are your measurements in the main review actually for “USB in -> headphone out” rather than “USB in -> line out” as it is written there? If that is the case, if
the DAC is not the limiting factor
then the "DAC Audio Measurements" are actually "USB in, Headphone out Audio Measurements". Then from the fact that SINAD for “USB in -> headphone out” is virtually the same as analog “line in -> headphone out” we can deduce that SINAD for DAC alone is much better.

if you have two subsystems cascaded with each having a SINAD of 80, the resulting SINAD will be 74 dB. If one is 90 dB, it almost makes no impact on the total SINAD as the 80 dB one dominates.
 
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prakosza

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#36
Well I'm not sure if it's even possible to check output of pure dac from this device as line output is already preamp.
 
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#38
That is exactly what the measurements are. If there is a DAC in there, I always use USB unless I say otherwise.
I understand you use USB but from my understanding you are still measuring the DAC by itself (usb->lineout), then the Amp separately (line in->phone out)? Sorry if I'm wrong and misunderstood your testing procedure.
If I am correct, then what I was saying is the USB->phone out performance may be worse due to some anomaly or weird stuff going on internally when DAC and amp are working together. Another way to put it is that summing the performance of the DAC by itself and the amp by itself (e.g. SINAD of dac + amps distortion and noise) may show better (or worse) results than USB->phone out.
 
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