This is a review and detailed measurements of the portable Fiio Q5s USB DAC and optional THX headphone amplifier (AM3D). It was kindly sent to me by a member. Q5s by itself costs US $300 from Amazon including Prime shipping. The AM3D THX AAA module costs an extra US $150 on Amazon including Prime shipping.
As it happens, the company was also kind enough to send one to me last year which I had yet to review! So I got a chance to test that version as well but briefly.
The form factor of Q5s is similar to other pricier stand-alone DAC/Headphone amps with chunky metal box:
There is a single micro USB connector at the bottom that provides both charging and also data connection to the PC. To use the THX module, you have to unscrew the standard one that comes with it ("AM3E") and plug in the THX one:
The volume control uses an ADC which converts is value and that is used to then adjust the level on both channels. This provided perfect channel matching but made me concerned about the performance of the volume control chip used in the middle.
On top you have Line In and Line Out. On the bottom on the THX module you have the 3.5 mm unbalanced jack and 2.5mm balanced.
DAC Audio Measurements
I connected the Q5s using USB and Line out and fired our normal dashboard test and got this disappointing result:
Look at the high spray of harmonic distortion to the right of our 1 kHz tone (the tall spike). I finished running all the DAC and headphone test which took two hours. I then went to graph the SINAD above in my spreadsheet and I see that I already had an entry for Q5s at SINAD of 100 db! What the heck?
I dig up the old unit with standard headphone amp and measure it and it too produces 90 dB SINAD. Frustration is starting to set in.
Aha! Maybe I used the headphone out. I plug the output cable into that and SINAD indeed shoots up to nearly 100 dB!
Back to the member unit with THX module it too measures well with headphone out:
With the headphone amp output, Q5s squeezes into second tier of all DACs tested:
At this point I realize all the tests are invalidated and I have to spend two more hours testing them all. Instead of punching my fist into the monitor, I calmed myself and ran the IMD test again, only to see no improvement whatsoever!
Why is IMD "SINAD" so poor at just 78 dB? The mystery was solved later when I ran the THD+N versus frequency:
Oh brother! Even getting rid of the effects of the poor DAC filter, there is a sharp rise in distortion as frequencies get lower. Dashboard SINAD is using a 1 kHz tone which doesn't see that. But IMD test tones do because it is the combination of 60 Hz and 7 kHz.
I fire up the analyzer at 20 Hz and get this horror show:
Our SINAD now is nearly half as much it was in the dashboard 1 kHz tone!
I ran a new test to show the issue in "time domain:"
The red sine wave is the 20 Hz tone. The blue one is the difference between it, and a pure 20 Hz sine wave, multiplied by 100 (otherwise the variations are too small to see). This is called the "residual" (null) signal. The highest variation is during negative swings of the power supply indicating poor capacity there.
Back to the DAC filter, this is what it looks like:
Gosh, here we go again catering to audiophile myths with such slow filters that allow a ton of ultrasonic junk to be produced by the DAC for no good reason. Worse yet, it causes the audible band to have an early droop:
As is typical, the roll off starts at 10 khz and by 20 kHz we are down a whopping 4 dB! The younger audience that uses this likely had the hearing that goes up that high so will be cheated out of some of the highs in their music. Maybe they will confused that for fidelity.
But the story is not on the right. It is on the left! What is that notch? At first I thought the analyzer was loosing data but it was not. Zooming in we clearly see the issue:
I tested the above on my other Q5s and it had the same problem with line out. Thankfully this is one test that improved with headphone out without this problem with either output module.
Why did they put this in there? It can't be an accident. Was there some audible noise there and they decided to filter it out or something? Blood is starting to boil big time by this point.
I had run the 32-tone test signal simulating "music" and got this poor output:
I thought no problem, I just switch to headphone output and the problem would be gone. No it was not! The output was identical out of the "THX" module! That power supply/low frequency issue is causing severe problem with this test.
Not everything is bad news. Dynamic Range is fine:
As is jitter:
Linearity is perfect:
Headphone Amplifier Tests
Here is our 3.5mm headphone output dashboard using the THX AAA module:
77 dB SINAD? How can this be? A THX module with this kind of performance? And this is in low gain with output not going much past 1.1 volt -- something a dongle can do better.
Switching to balanced output improves things:
But still nothing impressive.
Signal to noise ratio is worse than using the DAC:
The low output voltage kills any prospects of good power delivery into 300 ohm load:
At max gain and allowing for the distortion to rise we only have 18 milliwatts. If I measure at the knee of the curve as I usually do, power will drop to just 3 or 4 milliwatts!
I compared this to the standard module in high gain:
The noise level is a bit higher but both suffer identically from distortion and produce the exact same power.
Switching to 300 ohm gives us more power but still nothing that great:
Fortunately balanced output does deliver more power:
But with lots of distortion again.
I tested the frequency response and as I noted earlier, it doesn't have that notch:
Listening Tests
Please have some common sense. In the mood I am at the end of the above measurements puts me in no mood to listen to this device...
Conclusions
This was a painful review. So many variations to test. So many odd results. Two different devices. Two different amps. Three different outputs. Two different inputs. Maybe there is some explanation for the odd results that I am seeing but frankly, I don't have the patience to dig in more to find out. I see the words "THX" on a headphone amp and I expect world class performance. How did these measurements qualify for THX logo? What explains simple failures in frequency response of the line out?
I should say the company is very nice and cordial to deal with. But ultimately I have to go by what I have in front of me. Sadly it is not a functional product in my view. Yes, it produces sound. Yes, most people won't hear these issues but you are paying for great performance and you deserve to get it.
Needless to say, I can't recommend the Q5s with or without THX amplifier module.
-----------
As always, questions, comments, recommendations, etc. are welcome.
The panthers are asking for "fall" clothing. I keep telling them that is two months away but they don't listen. They say all the sales are now. With so many of them, no way I can afford to get them all new outfits. So please help me by donating what you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
As it happens, the company was also kind enough to send one to me last year which I had yet to review! So I got a chance to test that version as well but briefly.
The form factor of Q5s is similar to other pricier stand-alone DAC/Headphone amps with chunky metal box:
There is a single micro USB connector at the bottom that provides both charging and also data connection to the PC. To use the THX module, you have to unscrew the standard one that comes with it ("AM3E") and plug in the THX one:
The volume control uses an ADC which converts is value and that is used to then adjust the level on both channels. This provided perfect channel matching but made me concerned about the performance of the volume control chip used in the middle.
On top you have Line In and Line Out. On the bottom on the THX module you have the 3.5 mm unbalanced jack and 2.5mm balanced.
DAC Audio Measurements
I connected the Q5s using USB and Line out and fired our normal dashboard test and got this disappointing result:
Look at the high spray of harmonic distortion to the right of our 1 kHz tone (the tall spike). I finished running all the DAC and headphone test which took two hours. I then went to graph the SINAD above in my spreadsheet and I see that I already had an entry for Q5s at SINAD of 100 db! What the heck?
I dig up the old unit with standard headphone amp and measure it and it too produces 90 dB SINAD. Frustration is starting to set in.
Aha! Maybe I used the headphone out. I plug the output cable into that and SINAD indeed shoots up to nearly 100 dB!
Back to the member unit with THX module it too measures well with headphone out:
With the headphone amp output, Q5s squeezes into second tier of all DACs tested:
At this point I realize all the tests are invalidated and I have to spend two more hours testing them all. Instead of punching my fist into the monitor, I calmed myself and ran the IMD test again, only to see no improvement whatsoever!
Why is IMD "SINAD" so poor at just 78 dB? The mystery was solved later when I ran the THD+N versus frequency:
Oh brother! Even getting rid of the effects of the poor DAC filter, there is a sharp rise in distortion as frequencies get lower. Dashboard SINAD is using a 1 kHz tone which doesn't see that. But IMD test tones do because it is the combination of 60 Hz and 7 kHz.
I fire up the analyzer at 20 Hz and get this horror show:
Our SINAD now is nearly half as much it was in the dashboard 1 kHz tone!
I ran a new test to show the issue in "time domain:"
The red sine wave is the 20 Hz tone. The blue one is the difference between it, and a pure 20 Hz sine wave, multiplied by 100 (otherwise the variations are too small to see). This is called the "residual" (null) signal. The highest variation is during negative swings of the power supply indicating poor capacity there.
Back to the DAC filter, this is what it looks like:
Gosh, here we go again catering to audiophile myths with such slow filters that allow a ton of ultrasonic junk to be produced by the DAC for no good reason. Worse yet, it causes the audible band to have an early droop:
As is typical, the roll off starts at 10 khz and by 20 kHz we are down a whopping 4 dB! The younger audience that uses this likely had the hearing that goes up that high so will be cheated out of some of the highs in their music. Maybe they will confused that for fidelity.
But the story is not on the right. It is on the left! What is that notch? At first I thought the analyzer was loosing data but it was not. Zooming in we clearly see the issue:
I tested the above on my other Q5s and it had the same problem with line out. Thankfully this is one test that improved with headphone out without this problem with either output module.
Why did they put this in there? It can't be an accident. Was there some audible noise there and they decided to filter it out or something? Blood is starting to boil big time by this point.
I had run the 32-tone test signal simulating "music" and got this poor output:
I thought no problem, I just switch to headphone output and the problem would be gone. No it was not! The output was identical out of the "THX" module! That power supply/low frequency issue is causing severe problem with this test.
Not everything is bad news. Dynamic Range is fine:
As is jitter:
Linearity is perfect:
Headphone Amplifier Tests
Here is our 3.5mm headphone output dashboard using the THX AAA module:
77 dB SINAD? How can this be? A THX module with this kind of performance? And this is in low gain with output not going much past 1.1 volt -- something a dongle can do better.
Switching to balanced output improves things:
But still nothing impressive.
Signal to noise ratio is worse than using the DAC:
The low output voltage kills any prospects of good power delivery into 300 ohm load:
At max gain and allowing for the distortion to rise we only have 18 milliwatts. If I measure at the knee of the curve as I usually do, power will drop to just 3 or 4 milliwatts!
I compared this to the standard module in high gain:
The noise level is a bit higher but both suffer identically from distortion and produce the exact same power.
Switching to 300 ohm gives us more power but still nothing that great:
Fortunately balanced output does deliver more power:
But with lots of distortion again.
I tested the frequency response and as I noted earlier, it doesn't have that notch:
Listening Tests
Please have some common sense. In the mood I am at the end of the above measurements puts me in no mood to listen to this device...
Conclusions
This was a painful review. So many variations to test. So many odd results. Two different devices. Two different amps. Three different outputs. Two different inputs. Maybe there is some explanation for the odd results that I am seeing but frankly, I don't have the patience to dig in more to find out. I see the words "THX" on a headphone amp and I expect world class performance. How did these measurements qualify for THX logo? What explains simple failures in frequency response of the line out?
I should say the company is very nice and cordial to deal with. But ultimately I have to go by what I have in front of me. Sadly it is not a functional product in my view. Yes, it produces sound. Yes, most people won't hear these issues but you are paying for great performance and you deserve to get it.
Needless to say, I can't recommend the Q5s with or without THX amplifier module.
-----------
As always, questions, comments, recommendations, etc. are welcome.
The panthers are asking for "fall" clothing. I keep telling them that is two months away but they don't listen. They say all the sales are now. With so many of them, no way I can afford to get them all new outfits. So please help me by donating what you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/