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Review and Measurements of Topping DX3Pro DAC and Headphone Amp

amirm

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#1
This is a review and detailed measurements of the brand new, Topping DX3Pro DAC and headphone amplifier. The company kindly sent me a pre-production unit. I usually buy my Topping products unless they are not available in the market as was the case here. The retail price will be $219.99. I expect production to start soon given the high finish of the unit I have.

It is hard to fall in love with budget desktop audio products but there are exceptions and this is one of them. The Topping DX3Pro is darn cute!

Topping DX3Pro DAC and Headphone Amplifier Review and Measurement.jpg

The yellow LED as with the Topping D10 adds a much needed touch of color and uniqueness to the unit. The volume knob adds more to that sauce, making for a small box and you enjoy glancing at on your desk.

Surprising for a small unit, as seen in the picture, you get a remote control and all the functionality in its larger brother, the Topping DX7s. You can select the volume control to apply to line out, headphone out or both. So you could use this to drive powered speakers for example without a need for pre-amp and use the remote control as needed.

There is USB input of course and Toslink. For coax input, you actually get two of them! So if all of your sources are digital, you have a nice little pre-amplifier on your hands.

The volume control is digital of course and steps in 0.5 dB linearity all the way down to -99 dB.

There are selectable gains for the headphone out (0 and 9 dB) and filter settings. The unit supports PCM up to 768 kHz and up to DSD512.

Power is provided through a small switching power supply (double the size of typical phone chargers). All of my testing was performed using the provided power supply.

Setup was plug-and-play and I was relieved to see full compatibility with ASIO4ALL at 24 bit depth allowing me to proper test the unit without installing any drivers. Listening tests were performed using WASAPI interface in Roon.

The heart of the unit is the AKM AK4493 DAC chip. This is a departure from most of the Topping DACs (and many Chinese manufacturers) which use ESS DACs.

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

Measurements
Since the Topping DX3Pro is both a DAC and headphone amplifier, I am going to show performance using both output starting with the DAC section:

Topping DX3Pro DAC and Headphone Amplifier DAC Dashboard Measurement.png


We have our nice nominal output of 2 volts. Distortion/SINAD is very good, and solidly in "tier 2" ranking of DACs I have tested:

Topping DX3Pro DAC and Headphone Amplifier DAC SINAD Measurement.png


So not state-of-the-art but very competent nevertheless.

Dynamic range falls in the same bucket:
Topping DX3Pro DAC and Headphone Amplifier DAC Dynamic Range Measurement.png


Let's look at intermodulation distortion versus level:

Topping DX3Pro DAC and Headphone Amplifier DAC Intermodulation Distortion Measurement.png


Ah, we are finally free of the "ESS hump" at mid-levels. In this regard, except when we get to highest output levels, the DX3Pro beats even the Topping D50!

ESS really needs to pay attention to this situation and remedy whatever is causing that rise in mid-levels in their OEM designs.

Jitter and noise is busy but for a reason:
Topping DX3Pro DAC and Headphone Amplifier DAC Jitter Measurement.png


Until recently, I have not been running the J-test signal in full resolution. I have changed that now and the 250 Hz square wave in it shows interference between digital section and analog as seen by those series of spikes. Fortunately almost all are less than 120 dB so not an audible concern at all. Likewise the two that hug our main tone despite being at -110 are totally masked by the main tone at 12 KHz so inaudible.

Frequency response is boring (in a good way) and flat to -0.2 dB (spec is 0.5 dB):
Topping DX3Pro DAC and Headphone Amplifier DAC Frequency Response Measurement.png


THD versus frequency shows somewhat higher noise levels:
Topping DX3Pro DAC and Headphone Amplifier DAC THD vs Frequency Measurement.png


This is impacting linearity measurements:
Topping DX3Pro DAC and Headphone Amplifier DAC Linearity Measurement.png


That smooth exponential rise is just the noise floor of the DAC dominating. So it is not an offset error as we see many times (with jagged output). All else being equal, I rather seen noise here than non-linearities. I think this is a limitation of the AKM DACs relative to ESS parts.

Now let's switch outputs to headphone socket and see our dashboard view in low-gain/unity gain mode:
Topping DX3Pro DAC and Headphone Amplifier Dashboard Measurement.png


Pretty excellent! This is at max volume yet we get slightly better performance than even line out! SINAD rises to 108 from 106 dB.

Most of Topping products with headphone output have impedance of 10 ohm. That is dealt with now in DX3Pro:

Topping DX3Pro DAC and Headphone Amplifier Output Impedance Measurement.png


My measured impedance is usually higher than manufacturers due to use of more wires, etc.

The low impedance of 1 ohm means just about every headphone can be driven by the DX3Pro without fear of its frequency response being impacted.

Let's see the power output versus distortion using 300 ohm load:

Topping DX3Pro DAC and Headphone Amplifier Power at 300 ohm Measurement.png


Clipping never really sets in and as such, the output is distortion free all the way to max! SINAD even in high gain mode stays above 100 dB which is superb. This means if you have a 300 ohm headphone like Sennheiser HD-650, you can turn up the volume as much as you want and any distortion you hear is that of the headphone or the source.

Switching to 33 ohm load, we get far more power as expected:
Topping DX3Pro DAC and Headphone Amplifier Power at 33 ohm Measurement.png


We have half a watt using high-gain mode but we do clip past that. Topping spec is 1 watt at 1% distortion which is inline with my measurement.

In low gain mode you are distortion free up to max volume with power up to 0.12 watt.

Finally, let's look at channel imbalance versus volume control position:
Topping DX3Pro DAC and Headphone Amplifier Channel Imbalance Measurement.png


As expected, the digital volume control produces perfect response with essentially zero imbalance until you get to max volume attenuation of 99 db. No headphone amplifier using analog volume control comes remotely close to this kind of performance.

Listening Tests
I started my testing with Sennheiser HD-650 in high gain mode. Here, there was plenty of power and no hint of strain from the amplifier. Tonal response remained constant up to max volume which was quite loud. But not loud enough to make the cups flap in the wind. :)

Flapping of the cups was to come though the moment I switched to HiFiman HE-400i. Power was amazing and clarity was superb. As I type this review I have been listening to this setup and it could not be more satisfying.

Conclusions
As usual, Topping shows that it uses proper measurements and engineering talent to design its products. As with their other products, it is next to impossible to find many flaws in anything I measure. Yes, it is not state-of-the-art in all measures and falls just shy. But it makes up for it with its superb headphone stage with very low distortion levels, perfect channel matching, and lots of power coming from such a small package and power supply to feed it.

The switch from ESS to AKM has provided relief from intermodulation distortion that we have been seeing in so many DACs. Yes, there is a slight rise in noise as levels get down, impacting linearity measurements. That is a very worthwhile trade off in my book and I am glad Topping has made the change.

All in all, the DX3Pro does not obsolete every DAC and headphone amplifier out there. But it comes darn close and nails the functionality and performance needed in a moderately low cost unit. Add to that the attractive industrial design and it easily becomes one of my favorite desktop products. As such, I recommend the Topping DX3Pro wholeheartedly.


As always, all questions, comments and criticism is welcome.

-----
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gvl

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#2
Looks like a great little box that can simplify my desktop setup. I may bite.
 
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#3
Looks really good as an all-in-one product for people who aren't too deep in the audiophile hole to get and forget about a DAC/Amp upgrade in the future.

I have a couple question about what you mean by this:
The low impedance of 1 ohm means just about every headphone can be driven by the DX3Pro without fear of its frequency response being impacted.
What is the impedance you want where the frequency response will not be affected at all? For headphones I think its more forgivable for what about for something like IEMs which are more sensitive? For example, I've heard that the impedance of common smartphones nowadays are pretty close to 0 while your mobo has a higher impedance which will affect things. This has impedance of 1 Ohm while looking at something like the Hugo 2 which has 1.7 Ohms at several times the price.
The reason I ask is because I used to not worry about output impedance until one day I was trying some new IEMs through my mobo. Sound quality was extremely horrible as the frequency response in the bass was boosted significantly and smeared throughout. Off my phone, it sounded fine. So now I'm careful to look for anything that will be the most "transparent" so I get a consistent experience that isn't obscured by weird frequency response changes.
 

Sythrix

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#4
Agreed on the good looks. Looks kind of retro. Wouldn’t mind having that on my desk.

I noticed you didn’t give a bit-equivalent number on the linearity test. Is it determinable?
 

amirm

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#5
What is the impedance you want where the frequency response will not be affected at all?
The usual rule of thumb is that the headphone impedance should be 10X the amplifier impedance. And there, it only matters if there are variations in the frequency response. Otherwise all the frequencies will be attenuated by the same amount so it won't matter.

So look up the measurements of your headphones. If it is more than 10 ohms, you are good.
 

amirm

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#6
I noticed you didn’t give a bit-equivalent number on the linearity test. Is it determinable?
I stopped doing that due all the excitement it creates. :) Using my old metric, we get about 15.5 bits. But do note as I said in the review that this is just noise so much more benign than non-linearity that I see in other DACs.
 

Veri

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#7
Hey Amir I suppose you did all tests using USB? No real difference using the coax inputs I presume?

Looks like a really great unit. Just a little suprised by the jitter sidebands. I think at this price range they went with mid-range clocks..
 

amirm

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#9
Looks like a really great unit. Just a little suprised by the jitter sidebands. I think at this price range they went with mid-range clocks..
This is not a clock issue. All the bits in the J-test signal are toggle every 1/250th of a second. That causes the digital circuits to be exercised which in turn bleeds into the analog sections of the DAC. In the past measurements I used to suppress this but now I am letting it be seen.
 
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#10
cheap, lots of inputs, lots of outputs, enough power for seemingly anything short of an e-stat, seemingly audibly transparent -- what's not to like?

What is the impedance you want where the frequency response will not be affected at all?
FR will always be affected, but at some point it'll be by such a small amount you just won't be able to hear it.

Some used to recommend a damping factor of at least 8 for loudspeakers, but I don't think I've ever seen anyone do objective measurements for how much it affects headphones. Would be an interesting test to see :).
 
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#11
I was considering a D30+A30 stack, as the 10 ohm output-impedance won't be a problem for me, and will look damn nice next to my HD800.

I wish they went with a 6.35mm jack instead, or even better, 3.5mm + 6.35mm like we saw on the rHead, but I'm still interested :)

Any news on the price?
 

Grave

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#13
Wow, this looks awesome. It is great to see that Topping reduced the output impedance. This has less power than the Topping A30 I guess. I actually like the aesthetics of this better than the Topping D30/A30. I do not like that this only has a small headphones jack though.
 
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andreasmaaan

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#14
This is not a clock issue. All the bits in the J-test signal are toggle every 1/250th of a second. That causes the digital circuits to be exercised which in turn bleeds into the analog sections of the DAC. In the past measurements I used to suppress this but now I am letting it be seen.
Would it be possible please to perform your old J test on this DAC to give us a reference point for the new test?

And/or to do the new test on an old DAC?

Just something that allows us to place this unit’s J test performance in relation to other DACs...
 

SchwarzeWolke

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#15
Would it be possible please to perform your old J test on this DAC to give us a reference point for the new test?

And/or to do the new test on an old DAC?

Just something that allows us to place this unit’s J test performance in relation to other DACs...
Second that! Would be useful if you chose a really worse (Modi 2 Multibit) and a really great one (Benchmark, RME) to get a glimpse on the relative performance.
 

bennetng

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#16
Would it be possible please to perform your old J test on this DAC to give us a reference point for the new test?

And/or to do the new test on an old DAC?

Just something that allows us to place this unit’s J test performance in relation to other DACs...
I would like to see how it compares with Amir's ADI2-Pro (non-FS) in all tests (or at least dashboard, IMD, jitter and linearity) given the similarity of the DAC chip. I know it is not a fair comparison due the difference in price, just want to know more about AKM.
 
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#17
So it has better IMD but shine somewhat away from 16bits linearity. No free lunch for us it seems. Perhaps it will be fixed with the DX5 should they decide to make one (given how excellent the RME was). Nevertheless really surprised that they offer a remote out of the box for the DX3Pro while the bigger sibling doesn't, probably a production delay issues.
Don't want to keep you busy, but perhaps a filter test would be great. Another test that would be nice to see is the APTX-HD bluetooth with the LG G7. Both support the codec, and this will be a good setup to see how close the bluetooth codec performance fares with wired connection (though I imagine this won't be easy).
 

bunkbail

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#18
Great stuff. I need a DAC with remote control + Bluetooth functionalities and this cutie has it all. I'm 100% buying as soon as it comes out.
 

amirm

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#19
Another test that would be nice to see is the APTX-HD bluetooth with the LG G7.
Yes, I forgot to mention that this also has Bluetooth input. Will see if I can test it a bit.

Now I am going to sleep! :)
 
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