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:
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:
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:
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:
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:
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:
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:
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:
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:
Power increases naturally. Going down all the way to 33 ohm does generate clipping levels of output:
Output impedance is spec'ed at 0.5 ohm and measured somewhat higher (as it usually does) in my tests at 1.5 ohms:
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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The Oppo HE-2 comes in a luxurious packaging with the unit itself enshrouded in stitched leather:
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:
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:
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:
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:
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:
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:
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:
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:
Power increases naturally. Going down all the way to 33 ohm does generate clipping levels of output:
Output impedance is spec'ed at 0.5 ohm and measured somewhat higher (as it usually does) in my tests at 1.5 ohms:
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.
-----
If you like this review, please consider donating funds 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).
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