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Review and Measurements of Matrix Audio HPA-3U DAC & HP Amp

amirm

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#1
This is a review and detailed measurements of the Matrix Audio HPA-3U DAC and headphone amplifier. It is on kind loan from a member. From what I can tell, the HPA-3U came out around 2015. Matrix website shows a HPA-3U+. Not sure what the difference is. The HPA-3U sold for I think US $420. It seems to be a popular device as I see discussions about it and its balanced headphone amp only version even today. The latter, HPA-3B by the way, is also coming for review.

The HPA-3U has a "pro" audio look to it:

Matrix Audio HPA-3U DAC and Headphone Amplifier  Audio Review.jpg

The handle on the volume control is a bit slippery for my taste but otherwise, the volume control has a solid feel.

There is an input selector to choose between the internal USB and analog input. Next to it is a 3-way gain switch.

Here is the back panel and connectivity:

Matrix Audio HPA-3U DAC and Headphone Amplifier  Back Panel Audio Review.jpg

Nice to see mains power supply included in the unit.

The DAC only has USB input which is fine by me but not if you have other types of digital outputs.

The enclosure is quite deep by the way.

In use the HPA-3U got moderately warm. Nothing that would concern me but it will be a source of heat and power loss.

DAC Audio Measurements
I tested the internal DAC using the RCA outputs. Alas, their level changes with volume and go all the way up to 11+ volt, telling me they are just taps on the headphone jack. As such, which gain you use can make a small difference when measured at our nominal 2 volt output:

Matrix Audio HPA-3U DAC and Headphone Amplifier DAC Audio Measurements.png


Gosh, this is disappointing. We are so spoiled by the higher-end and modern offerings from Matrix Audio that this kind of performance is a real let down. Plotting the SINAD (signal over noise and distortion) shows that the HPA-3U barely makes it into our third quadrant of all DACs tested:
Best Audio DACs Reviewed and Measured.png


Given this performance and the fact that RCA out is essentially the same as headphone out, I decided to not run more DAC tests and jump into headphone testing using analog input.

Headphone Amplifier Measurements
Using my Audio Precision as signal generator, and setting the input and output levels to 2 volts, we get this dashboard:

Matrix Audio HPA-3U DAC and Headphone Amplifier HP Audio Measurements.png


That is quite an improvement. Not only is our SINAD much higher, but what is there is mainly dominated by mains hum. The actual distortion products are vanishingly low at less than 125 dB! The DAC is clearly the weak link in HPA-3U.

Reading comments online, it seems that with ultra sensitive IEMs someone could hear the hum and proceeded to put shielding around the transformer which got rid of it. So close proximity of the transformer in the case may be the cause here.

Indeed, SNR tests with just 50 millivolt of output indicates the same:
Matrix Audio HPA-3U DAC and Headphone Amplifier HP SNR Audio Measurements.png


Headphone Amplifier SNR 50 Millivolt Audio Measurements.png


Frequency response while flat within audible band, has a bit too much roll off in my view:
Matrix Audio HPA-3U DAC and Headphone Amplifier HP Frequency Response Audio Measurements.png


Here is the intermodulation distortion versus output level (NOT input):
Matrix Audio HPA-3U DAC and Headphone Amplifier HP IMD Audio Measurements.png


We see that at low gain, while noise is higher, once we approach maximum power, we match the performance of our reference Massdrop THX AAA 789 (pink line)! WIth highest gain setting, we definitely have higher noise level but also generate more power. Indeed we can see that in our THD+N versus power:

Matrix Audio HPA-3U DAC and Headphone Amplifier HP THD 300 Audio Measurements.png


With low to medium gain, the unit never clips with 2 volt input which DACs normally produce over RCA outs. Distortion levels are quite low and the disparity with THX AAA 789 is just in noise level.

With highest gain, the HPA-3U produces 360 milliwatts of power which is excellent. My criteria here is just 100 milliwatts so you should be perfectly fine driving very high impedance headphones to very high sound levels. THX AAA 789 would need to resort to its balanced output to match the HPA-3U.

Performance degrades more with 33 Ohm load which emphasizes current delivery:
Matrix Audio HPA-3U DAC and Headphone Amplifier HP THD 33 Audio Measurements.png


But still quite respectable. On power side, 2.3 watts is available which should drive just about any low impedance headphone to deafening levels.

Output impedance is comfortably low at 1.4 ohm:
Best headphone amplifier output impedance measurement.png


Channel balance is surprisingly good down to minimum level:

Matrix Audio HPA-3U DAC and Headphone Amplifier HP Channel Imbalance Audio Measurements.png


Headphone Listening Tests
I started my testing as usual with Sennheiser HD-650. At high gain, you have incredible amount of power, so much so that I was scared to even approach max volume let alone leaving it there. Bass and dynamics are incredible as a result with no hint of distortion.

Switching to the other extreme using my Drop Mrspeakers Ether CX repeated the above experience, we have copious amount of power available. No hint of distortion was there and I could drive them as hard as I wanted.

Conclusions
While probably not an audible concern, the measured performance of the DAC in HPA-3U is disappointing. The headphone amplifier though has tons and tons of power with no hint of distortion. The high mains noise though may rule it out of using it with sensitive IEMs.

Subjective listening tests which included its DAC by the way, showed that performance there is excellent across the board with non-IEM headphones (I did not test with IEMs).

Overall, I recommend the HPA-3U as a strong headphone amplifier. You can start with it and maybe add another DAC if you are after best measured performance. Or wait for the review of the HPA-3B and see if that is worth getting and pairing with an external DAC.

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

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maxxevv

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#2
Without the mains noise, the amp section looks to be able to get pass the -110dB territory, maybe even better. But that's purely speculative there.

Will be interesting to see the the 3B version's measurements as that's the one I have. And yes, on both the HD6XX, HE4XX and HD800, the 3B has an endless amount of smooth power. Even at its lowest gain.
 

Nango

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#3
Well, DAC-wise I think we are more than covered with all that KTB and EIDA 9038 stuff, but the upcoming review for HPA-3B could be a real option to the 789 THX if you need a balanced headphone output the JDS Atom lacks. Cant await the HPA-3B review :D and hope it doesn't start with the decapitated panther !!!!!
 
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#6
Are you looking for linearity test to make the DAC look better or worse?
For completeness sake. The measurements shall decide its faith ;)
 

Nango

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#10
Do they still sell the HPA-3B? You can still find a page about it on their website https://www.matrix-digi.com/en/products/313.html
But on that page, the link to buy it doesn't work. You also can't even get to that page from their main product list. I can't find it being sold anywhere else either.
https://www.audiophonics.fr/en/sede...s-a-balanced-headphone-amplifier-p-10038.html

Not in stock now (tagged at 299€ and I wouldn't pay higher than this!!), maybe available soon again.
 

maxxevv

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#11
Its discontinued as far as I'm aware. So if its out of stock, its not coming back.
In fact , I got mine off the last Massdrop window over a year ago.
 

Nango

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#12
Last edited:

Nango

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#14
In that case @amirm I suggest DO NOT measure this amp. Imagine it measures like 789 THX or even better on its balanced output and it's again not available!! NIGHTMARE!!!
 
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#16
3U+ is replaced with the 1793 chip used by 3U to CS4398, but it seems that their back panel keeps the name 3U
 
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#17
I'm interested in this one just for the portability. I understand there are better options in the price range for desktop setups. Wondering though, how the 3B (or 3U+) would compare to my Topping NX4 DSD. From the review, it seems clear that the nx4 has a better DAC, but this thing has a better amp.
 

maxxevv

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#18
I'm interested in this one just for the portability. I understand there are better options in the price range for desktop setups. Wondering though, how the 3B (or 3U+) would compare to my Topping NX4 DSD. From the review, it seems clear that the nx4 has a better DAC, but this thing has a better amp.
This is not "portable". And its barely "transportable" too given its dimensions and weight.

Its 285 × 142 × 49mm and 1.7kg. I highly doubt you would consider that as being " transportable" on a regular basis.
I certain won't do it with my HPA-3B which is dimensionally and weight wise almost identical.
 
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#19
I'm interested in this one just for the portability. I understand there are better options in the price range for desktop setups. Wondering though, how the 3B (or 3U+) would compare to my Topping NX4 DSD. From the review, it seems clear that the nx4 has a better DAC, but this thing has a better amp.
It has tons of power compared to nx4. If you don't have high-impedance headphones, there is nothing to worry about, nx4 is a pretty good device.
 
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#20
Yeah I like the nx4. I'll probably get a thx 789, but I really don't feel like waiting for it. Also want to get the okto dac-8. Can't resist the aesthetic.
 
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