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Review and Measurements of HIFIMAN EF2A DAC and Headphone Amp

Timbo2

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#41
Amir,

If you are burned out on DACs and headphone amplifiers, I’m happy to lend you my Nobsound NS 10P minature tube preamplifier. I have the original Chinese tubes and set of Russian replacements.

Amazon page for description

I’ve been a solid state guy for my entire audio career and wanted to try the “tube sound” everybody talks about. This lets me give it a shot for little money. I use it to turn my O2 amp into a hybrid. Subjectively, it does seem to add some euphonics. It has a gain of 1.5x or so, and given the design of the O2 you can overload the amp on high gain with maximum volume on the preamp.

Naturally it comes with zero instructions. I can’t figure out if the tone controls are supposed to be at 12:00 for a neutral position and attenuate or deattenuate as you go left or right. At least by ear that is the way they sound. Also no idea what the curves look like, so that also might give you something to measure with your new toy!

I looked it as a fun way to add tone controls to my headphone setup. I’d say 9 out of 10 times I don’t use it when I’m listening.
 

amirm

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#42
Amir,

If you are burned out on DACs and headphone amplifiers, I’m happy to lend you my Nobsound NS 10P minature tube preamplifier. I have the original Chinese tubes and set of Russian replacements.
I am actually not burned out myself on DAC tests although some members are. :) But a break from them and investigating a new type of product to measure was fun.

And yes, I don't mind measuring amps. I have a bunch in my queue. Give me some time to clear my current backlog and then we can get into that.
 

Timbo2

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#43
I am actually not burned out myself on DAC tests although some members are. :) But a break from them and investigating a new type of product to measure was fun.

And yes, I don't mind measuring amps. I have a bunch in my queue. Give me some time to clear my current backlog and then we can get into that.
Sure, shoot me a message or put a general note out when you’ve cleared your backlog and are looking for more gear.
 

amirm

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#44

amirm

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#46
nterestingly I found this Amazon review from nearly 2 years ago, and it almost prophetically predicts the test results you obtained.
He is indeed. His is a huge hack job with that daughtercard PCB. This seems to be an analog headphone with a DAC added to it without proper design.
 

amirm

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#47
Here is the belated linearity measurement for HiFiMAN EF2A:
Hifiman EF2A DAC and Headphone Amp linearity Measurement.png


As we see, the news here is quite sad. This unit uses an ancient 16 bit USB DAC. But even there, its output doesn't get accurate (to 0.1 dB) until way, way under at about -68 (as opposed to -96). That represents about 11 bits of accuracy.

As I noted in the review, when used with USB input, it also clips and that is apparent in the linearity test. At -4 dB the output becomes wrong indicating distortion.

All in all, one of the worst showings of any DAC I have tested.
 

Jimster480

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#48
Here is the belated linearity measurement for HiFiMAN EF2A:
View attachment 13464

As we see, the news here is quite sad. This unit uses an ancient 16 bit USB DAC. But even there, its output doesn't get accurate (to 0.1 dB) until way, way under at about -68 (as opposed to -96). That represents about 11 bits of accuracy.

As I noted in the review, when used with USB input, it also clips and that is apparent in the linearity test. At -4 dB the output becomes wrong indicating distortion.

All in all, one of the worst showings of any DAC I have tested.
have you tested one that is worse?

I'm actually interested in seeing how one of those $4 USB soundcards measures.
 

amirm

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#49

Valorum

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#50
Thanks for the extra testing, Amir! This quality and performance seems about par for Hifiman, with their infamous headphone headband cracking issues.
 
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