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Review and Measurements of Oppo HE-2 SE DAC and Headphone Amp

amirm

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#1
This is a review and detailed measurements of Oppo HE-2 SE DAC and headphone amplifier. It is on kind loan from a member. Retail price per Oppo website is $299 but I see it as used from $430 and up on Amazon. I wonder if that is because as with their Blu-ray player business, Oppo is getting out producing this device too.

The Oppo HE-2 comes in a luxurious packaging with the unit itself enshrouded in stitched leather:

Oppo HA-2 SE DAC and Portable Headphone Amplifier Review and Measurements.jpg


Intentionally or not, the look at feel of the unit seems to cater more to older clientele than the younger and typical market for headphone and DAC amplifiers.

The unit sports an ESS ES9028-Q2M so it targets high performance.

Boatload of cables and connectors come with the unit which satisfy every type of connection to every device imaginable including selection of right-angle adapters/cables.

I am sure you all are anxious to see how it measures so let's get into that.

Measurements
Seeing how the HA-2 SE touts its DAC subsystem and has dedicated line output, I thought I test that subsystem independent of its headphone amplifier. So let's look at Dashboard view of the DAC:
Oppo HA-2 SE DAC and portable headphone amp line out measurement.png


While the output level at 1 volt RMS matches the spec, it is half of what we like to see here. Nominal voltage of 2 volts needs to be provided to drive all pre/power amplifiers. Otherwise you may not be able to achieve maximum power level.

THD+N and SINAD (signal over power of distortion and noise) falls comfortably in the tier of portable devices:


Oopo HA-2 SE SINAD measurement.png


It falls way short of Topping DX4 DSD however. No doubt the lower output level hurts the HA-2 SE here.

This is reflected in intermodulation distortion versus level:

Oppo HA-2 SE DAC and portable headphone amp line out IMD vs Level measurement.png


Performance is fair bit better than the DAC in my laptop but falls short of Topping D50 DAC. So you are not going to get a desktop replacement DAC here.

Just the same, Jitter and Noise measurements show fair bit of interference, noise and some jitter components:


Oppo HA-2 SE DAC and portable headphone amp line out jitter measurement.png


These may be USB related noise in which case, how good or bad they are will be computer/host dependent.

Surprisingly though, the HA-2 SE nails the linearity test:
Oppo HA-2 SE DAC and portable headphone amp line out linearity measurement.png


Let's switch to headphone output and see how she does. Here, I got thrown off for a bit as I could not get any measurements with my Analyzer yet plugging in a headphone would produce the intended output! Noticing that there was a one second pause before sound would start on my headphones, I figured there must be a protection circuit that detects unusual conditions and shuts off the output. In this case, the default 100 K ohm impedance of my analyzer was causing the HA-2 SE to mute its output. Setting that to typical headphone loads (as high as 600) resolve this. Alas, this means that you can't use the headphone output to drive pre/power amps as they too will present a high impedance to HA-2 SE.

Let's start with frequency response with and without the boost switch enabled:

Oppo HA-2 SE DAC and portable headphone amp frequency response measurement.png


Some channel imbalance is visible which we will dig into later.

Typical of these implementations, bass boost does a lot more than boosting bass with the increase going as high as 2 kHz.

In flat setting there is some droop at 10 Hz but it is essentially flat to 20 Hz.

Power into 300 Ohm was pretty low:

Oppo HA-2 SE DAC and portable headphone amp power at 300 ohm measurement.png


There is insufficient gain to drive the output stage into clipping. So we get somewhat less power but it is clean to the end.

26 milliwatts is decent amount of power to drive such loads but in my school, the more the better. :) Here the Topping NX4 DSD delivers 150 milliwatts or nearly 7 times more power.

The situation remains roughly the same into a 150 ohm load:

Oppo HA-2 SE DAC and portable headphone amp power at 150 ohm measurement.png


Power increases naturally. Going down all the way to 33 ohm does generate clipping levels of output:

Oppo HA-2 SE DAC and portable headphone amp power at 33 ohm measurement.png


Output impedance is spec'ed at 0.5 ohm and measured somewhat higher (as it usually does) in my tests at 1.5 ohms:
Oppo HE-2 SE Output Impedance measurement.png


This is pretty good and unlikely to be an issue.

Listening Tests
Since I still have the Topping NX-4 DSD on kind loan, I compared it to the Oppo HA-2 SE after matching levels. In AB testing at moderate to good levels, I could not detect any noticeable difference in blind AB testing.

Turning up the levels with my Sennheiser HD-650 headphones, the Topping NX4 DSD would run rings around the Oppo with far higher output levels.

Conclusions
The Oppo HA-2 SE is an attractive unit and produces good performance. Alas, it lacks perfection and best in class execution. Its DAC has some warts such as excessive noise and jitter and anemic output level. Its headphone amplifier is clean with low impedance but does not have competitive amount of power.

Net, net, I won't come and chase you if you buy the Oppo :). But I encourage you to look at other options if you are in the market for a headphone amplifier and DAC combo.

As always, questions, comments, corrections, etc. are welcome.

-----
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rmo

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#3
I had nothing but problems with this dac playing Tidal tracks downloaded on a sd card .

Lots of cutouts

Thus I wasn’t

impressed and you are better off using a Cyrus soundkey or something else .

Hasn’t Oppo discontinued this lousy dac?
 

JJB70

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#6
This one is particularly interesting as the HA-2 SE was one of those products that magazine reviewers seemed to latch onto and wax lyrical about it. Looks like based on measurement it didn't quite justify some of the laurels it was awarded.
 

Jimster480

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#7
There were so many good reviews on this unit... I almost bought one when I was debating on getting a "portable DAC/Amp" but I decided to wait for the NX4 DSD. And alas by the time it came out I actually had no need for a portable DAC/Amp.

Looking at this review I'm glad I waited. Now I know if the time comes where I do need one, I will certainly get the NX4 DSD.
I dont think anything has unseated its performance crown yet?
 

Johnb

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#8
Hello, stop for one second. Although NX4 DSD seems to be cleaner per your review, the output power is nearly identical. You mentioned 50 mW at 300 ohm vs OPPO 26 mW and at 33 ohms, 150 mW Vs OPPO 158mW. These are your numbers! Obviously, NX4 is better and cheaper, but maybe battery life might come into play as well.
 

rmo

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#9
Hello, stop for one second. Although NX4 DSD seems to be cleaner per your review, the output power is nearly identical. You mentioned 50 mW at 300 ohm vs OPPO 26 mW and at 33 ohms, 150 mW Vs OPPO 158mW. These are your numbers! Obviously, NX4 is better and cheaper, but maybe battery life might come into play as well.
I haven’t been too impressed with the NX4 battery life
 

jhaider

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#10
I had one for a couple years and traveled extensively with it. I mentioned it in my "Traveling While Audiophile" essay. https://hometheaterhifi.com/blogs/traveling-audiophile-primer/

I sold it recently, because it never really worked with iPhone X. It would disconnect at times and was useless as a power bank. I did not and would not pay the price it sold for...

When it worked it had plenty of power and low enough noise for NAD HP50. I always thought the cheap-looking plastic Headroom Total BitHead drove Sennheiser HD580 a little better.
 

rmo

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#11
I had one for a couple years and traveled extensively with it. I mentioned it in my "Traveling While Audiophile" essay. https://hometheaterhifi.com/blogs/traveling-audiophile-primer/

I sold it recently, because it never really worked with iPhone X. It would disconnect at times and was useless as a power bank. I did not and would not pay the price it sold for...

When it worked it had plenty of power and low enough noise for NAD HP50. I always thought the cheap-looking plastic Headroom Total BitHead drove Sennheiser HD580 a little better.
With my iphone it would disconnect frequently. I returned it within the 30 day window on Amazon. Now you now why they discontinued the dac.
 

NorthSky

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#12
Oppo Digital doesn't make products anymore...Blu-ray players, headphones, DACs, headphone amps, etc. Support for them will continue though, and warranties will be respected. This was announced last April 1st/2nd. ...No joke.

Oppo is putting its energy where the money is...portable cell phones...Androids.

I have read this thread and I thought of officially mention it, because of the uncertainty expressed. This is old news, almost seven months (6.5).

https://www.theverge.com/circuitbre...i-fi-audio-disc-player-oppo-digital-shut-down

The article doesn't mention headphones amps and DACs but it's part of all Oppo Digital products. ...It is the entire Oppo Digital product line division.
_____

 
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jhaider

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#13
With my iphone it would disconnect frequently. I returned it within the 30 day window on Amazon. Now you now why they discontinued the dac.
Mine worked great with an iPhone 6S, but sucked with the X. I believe they discontinued this DAC when they, as mentioned above, shut down their audio division.

Too bad. The industrial design and build quality were excellent. I'm still looking for a competent travel headphone amp. The miniDSP HA-DSP had the best chance, but miniDSP abandoned the iOS market.
 

rmo

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#14
Mine worked great with an iPhone 6S, but sucked with the X. I believe they discontinued this DAC when they, as mentioned above, shut down their audio division.

Too bad. The industrial design and build quality were excellent. I'm still looking for a competent travel headphone amp. The miniDSP HA-DSP had the best chance, but miniDSP abandoned the iOS market.
It's really sad because I thought the dac sounded pretty good.... when it worked.
 
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