• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Review and Measurements of FX Audio DAC-X7 DAC & Amp

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
19,475
Likes
20,535
Location
Seattle Area
#1
This is a review and Measurements of the FX Audio DAC-X7 DAC and headphone amplifier. An overseas member was interested in it and donated the shipping cost for me to buy it locally. The cost on Amazon is US $189 with free shipping in US. DAC-X7 uses the same AKM 4490 as Topping DX3 Pro so makes for a good comparison as you will see later. DX3 Pro costs more though but includes Bluetooth.

While typical of this class of products, the DAC-X7 adds a touch of class with a blue display:

FX Audio DAC-X7 DAC and Headphone Amplifier Audio Review.jpg

The display while very small, is more legible than likes of SMSL for example.

The back panel is more or less what you expect:

FX Audio DAC-X7 DAC and Headphone Amplifier Back Panel Audio Review.jpg

There is however an Aux in which I did not have a chance to measure as all of my testing is with USB input.

The external power supply is a bit unusual in that it has a detachable power cord so you don't have to find a large slot on your power strip to fit it.

Dac Audio Measurements
The rear RCA outs are variable which tells me they are a tap on the output of the headphone amplifier with possibly addition of an inline resistor. So I adjusted the level to get 2 volts and measured its overall performance:
FX Audio DAC-X7 DAC and Headphone Amplifier DAC Audio Measurements.png


So nothing broken but THD+N/SINAD (signal over noise and distortion) is more than I like to see. Second harmonic dominates and together with noise establishes the SINAD of 97 dB which is good enough for CD music:
FX Audio DAC-X7 DAC and Headphone Amplifier DAC SINAD Audio Measurements.png


Keeping score against Topping DX3 Pro, the DAC-X7 is behind by nearly 10 dB.

Jitter test shows a lot of noise/spurious tones:
FX Audio DAC-X7 DAC and Headphone Amplifier DAC Jitter Audio Measurements.png


Not happy about that but they shouldn't be audible.

Linearity likewise shows less than excellent performance:
FX Audio DAC-X7 DAC and Headphone Amplifier DAC Linearity Audio Measurements.png


The general theme is good but not great.

Headphone Amplifier Measurements
Let's see how much the DAC-X7 can pump into a 300 ohm load:
FX Audio DAC-X7 DAC and Headphone Amplifier Power into 300 ohm Audio Measurements.png


We get respectable level of power of 86 milliwatts. That is shy of Topping DX3 Pro but should still be plenty for most headphones. As with DAC measurements though, we see higher noise and distortion.

Switching to 33 ohm load which exercises current delivery we get:

FX Audio DAC-X7 DAC and Headphone Amplifier Power into 33 ohm Audio Measurements.png


Once again we have ample power but even more noise and distortion.

Output impedance out of the 1/4 inch jack is comfortably low but not on the 3.5 mm output:
Headphone Amplifier Output Impedance Measurements.png


Would have much preferred a low-gain setting as DX3 Pro has rather than just an in-line resistor as is implemented here. The resistor will cause power drop and change the frequency response of some headphones. So stay with the 1/4 inch jack unless you are hearing a lot of background noise.

Channel matching is excellent as is typical of these DAC+Headphone amp combos that attenuate using the DAC volume control:
FX Audio DAC-X7 DAC and Headphone Amplifier Channel Balance Audio Measurements.png


Headphone Listening Tests
Starting with my Sennheiser HD-650 headphones, I had plenty of power with no sign of distortion. I could hear all the detail in the music for a satisfying experience with plenty of bass as the measurements predict.

With Hifiman HE-400i I also had plenty of power and very good fidelity. However, on some tracks I could get the unit to distort above 80% volume. This is very loud though so not a concern in usual listening. Just a note that if you have a low impedance headphone that is less efficient than the HE-400i, then you may be hearing more distortion.

Conclusions
You pay less, and you get less. The FX Audio DAC-X7 costs less than Topping DX3 Pro and delivers less features (no Bluetooth) and less performance across the board. If you want the best in budget combo DAC and headphone amp, my recommendation remains the Topping DX3 Pro. But if every penny counts, and you can't wait for a sale on DX3 Pro, the FX Audio DAC-X7 makes a decent substitute. Some corners have been cut to get the cost down but the design seems sound, pun intended.

This unit is available for sale. Please start a conversation with me if you want to buy it.

-------------
As always, questions, comments, recommendations, etc. are welcome.

I got contacted by Google saying I am violating their decency policies by posting pictures of pink panthers nude! Never mind that I don't use Google advertising for it to matter but just in case one day I do, please donate money so I can buy some clothes for my panthers using:

Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
 

daftcombo

Addicted to Fun and Learning
Patreon Donor
Joined
Feb 5, 2019
Messages
756
Likes
301
#4
Thanks you Amir for your review.
It is good performance for CD listening but not state-of-the-art for more.

A few more questions:

Which version is it that you got? V10 like on this picture?
https://static.qobuz.com/info/IMG/jpg/Filter_HP_amp_.jpg
or V4 like on Maty's?

At which volume on the screen did you do the tests ?
Did you install drivers ?
Are FR magnitude and phase flat ?
Could you test IMD ?
Could you test optical in and coaxial ?

Also, one weird thing is that you found better distortion than on the specs:
"RCA level output: 1.9Vrms
RCA distortion rate: 0.03%
RCA signal noise: 108dB"
 
Last edited:

JohnYang1997

Addicted to Fun and Learning
Joined
Dec 28, 2018
Messages
876
Likes
356
#5
I personally will stay away from any with NFJ in the name or associated. This is 100% personal. If anyone of you are Chinese or have a Chinese friend, he would know.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
19,475
Likes
20,535
Location
Seattle Area
#7
Also, one weird thing is that you found better distortion than on the specs:
"RCA level output: 1.9Vrms
RCA distortion rate: 0.03%
RCA signal noise: 108dB"
I read those and they were strange.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
19,475
Likes
20,535
Location
Seattle Area
#8
At which volume on the screen did you do the tests ?
Did you install drivers ?
I adjusted the volume to get 2 volt. Max was over 5 volt on RCA.

And no drivers. Plug and play under windows 10.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
19,475
Likes
20,535
Location
Seattle Area
#9

daftcombo

Addicted to Fun and Learning
Patreon Donor
Joined
Feb 5, 2019
Messages
756
Likes
301
#11
I personally will stay away from any with NFJ in the name or associated. This is 100% personal. If anyone of you are Chinese or have a Chinese friend, he would know.
Can you be a bit more precise? (In a private message if necessary.)
 
Joined
Aug 6, 2018
Messages
33
Likes
16
Location
Sweden
#13
I adjusted the volume to get 2 volt. Max was over 5 volt on RCA.

And no drivers. Plug and play under windows 10.
Did you note how the performance was at max output? Also is there a techincal reason as to why higher than 2 volt output is usually limited to balanced outputs other than convention?
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
19,475
Likes
20,535
Location
Seattle Area
#15
Did you note how the performance was at max output? Also is there a techincal reason as to why higher than 2 volt output is usually limited to balanced outputs other than convention?
I did try higher output. It made no difference. As to 2 volt, there is a danger of overdriving the follow on device, causing distortion there.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
19,475
Likes
20,535
Location
Seattle Area
#16
I personally will stay away from any with NFJ in the name or associated.
What does NFJ mean? Why is there two names on this device? FX Audio and NFJ.
 

JohnYang1997

Addicted to Fun and Learning
Joined
Dec 28, 2018
Messages
876
Likes
356
#18
The bottom line is, as shown in the measurements, it's not that bad of a product. It's just personal...
 
Joined
May 4, 2019
Messages
32
Likes
25
#19
Oh well. NFJ was initially on Bilibili video platform. He was streaming regularly educating people technical terms in audio and how to choose earphones, dacs, amps and reviews. The thing is, as hard as he tried, every sentence has a mistake. And it was extremely misleading. That's all fine and nobody cared.
Then he started saying that he can make good in ear headphones, good amplifiers etc. First product was a tube headphone amplifier, which as you expected looks great but was faulty and horrible sounding. Then he made earphones that has frequency response resembles rollar coaster. And insanely ****** phase response and acoustic performance. The housing was literally resonating with the sound. He even went on Chinese TV channel with successful crowd fund (which is kinda big thing). He has zero professionals, and shits on customers. The products break easily and he told them methods to modify the headphones in such way may break eg planars that magnets will hit each other sandwiching and destroy the diaphragm. Chinese hifi community hate him. It's like the worst thing ever.
As time went on he kinda just faded away and not in the spotlight anymore. What he did was explore the oversea market. Here we are. As he learned, he team up with other technical teams to make these things. Sure some things are not horrible. But the name of him alone is disgusting. Yeah that's personal. I fucking even helped him how to tune the earphones, teaching him harman target and what to expect and people's preference and tweaks. He proceeded to ignore and made such ****** products. DISGUST-ANG!
NFJ和脑放君是同一个东西吗,我看他日本官网好像只是一个一个飞想的采购商啊?如果有我不知道的细节请详细,不懂你国hifi圈:p
 

daftcombo

Addicted to Fun and Learning
Patreon Donor
Joined
Feb 5, 2019
Messages
756
Likes
301
#20
NFJ和脑放君是同一个东西吗,我看他日本官网好像只是一个一个飞想的采购商啊?如果有我不知道的细节请详细,不懂你国hifi圈:p
Can you say it again in english please? Google translate gives:
Is NFJ and Brain Fangjun the same thing? I think his Japanese official website seems to be just a buyer who wants to fly? If there are details I don't know, please do not know your country hifi circle
 
Top Bottom