Hello everyone,
This is a review and measurements of the Topping DX1 II Dac and headphone amplifier.
I bought it from Topping site and received it rapidly. I got it for around 120$.
Topping DX1 II - Presentation
This little device acts as a DAC (USB or Optical input), with line level RCA/Balanced(mini TRS) output, and headphones amplifier (balanced and unbalanced outputs). On top, there is a digital pass-through (optical input to optical output) to chain these items and/or feed another DAC/Device. Last, and not least, we get PEQ (3 presets can be recorded).
Front knob is digital volume acting prior to conversion, and in fact even before the digital filter (I tested) at very precise steps as indicated on the front display.
The back of the unit is busy:
We have RCA and 4.4mm Balanced output, a digital input and a much less common digital output.
Inside we get high resolution ES9039Q2M DAC, and high power amplification.
User Experience
It was easy to configure the Topping with my Windows 11 computer since I had nothing to do
The operating system saw the Topping and named it "DX1 II". Interestingly, it sees it as an input too, and I was hoping I could get the optical input to feed my computer, but no. I don't know if that's expected. I tried with the driver that Topping published but I wasn't successful either. So actually, this digital input only serves to feed the internal DAC for conversion. EDIT: @Berwhale informed me that an analog input is available with front 3.5mm jack, which makes sense.
The digital output willrelay a digital signal from the computer, meaning the Topping can be used as a DDC (Thank to @staticV3). That optical output will also route the SPDIF input to SPDIF output. And if I initially thought the Topping would not act as DDC, it is because when deactivating the EQ, I no longer get digital output, not sure if that is wanted or a user error of me. END EDIT
The menu offers several possibilities to tune the device, High/Low Gain, Front/Rear outputs activation, digital filter selection, and few others, one of which one is a setting for Optical input compatibility which had no effect on my side (see the review).
Measurements
All measurements performed with an E1DA Cosmos ADCiso (grade 0) in mono mode, the Cosmos Scaler (100kohms from unbalanced input) and APU (when required) for analog outputs, and a Motu UltraLite Mk5 for digital.
This review was performed with the firmware V2.69.
Topping DX1 II - Measurements - USB input to line level output
From Rear connectors (into 100kΩ and 200kΩ), I measured:
Let's start measurements with USB to rear RCA outputs.
The below is the standard dashboard, 1kHz @0dBFS, volume down to -0.5dB so the output is 2.1Vrms as to align with @Amir's measurement of the same. And I aligned the SINAD (or THD+N) calculation to the regular span of Amir, that is 10Hz to 22.4kHz:
Impressive results for unbalanced output. This is the right channel, at 120.8dB SINAD, and left one is the exact same. It brings this little device at the top of the excellent performers, nice!
When increasing to full 2.3Vrms output, the SINAD is 121dB.
EDIT: I initially had an issue with rear balanced output, with lots of Power Supply leakage, and after leaving the device on for many hours, it is all gone. So here is the view at full output voltage (5Vrms):
This is a SINAD of 123.3dB.
At 4Vrms output (vol at -1.5dB), I get a SINAD of 122.7dB average between the two channels (122.8dB R and 122.6dB L). This is SOTA performance!
END EDIT
-----
Let's go back to to RCA output. The very good results with 1kHz sine tone continue with multitone:
We get roughly 21+ to 23 bits of distortion-free range, again excellent! That said, note an obvious increase of distortion at higher frequencies, but still bellow -125dBr!
And note that in balanced mode, the MT is a little better, although that won't make a difference to your ears:
That is true best in class (ignore the spike at 150Hz, I get it sometimes, it's from my testing gears).
----
Next is the bandwidth and options for oversampling filters (8 of them!), as shown below:
Actually, this is exactly the same as the Topping D50III and I share the recommendation of @amirm on that one: Go filter 3, it offers the best attenuation, least ringing and audio bandwidth is protected (fully flat).
----
To keep going with the standard reviews of Amir, let's have a look at THD+N vs frequency with a bandwidth extended to 90kHz to include distorsion and noise, and that is a rough test:
Excellent results here, best in class if you allow me, especially with unbalanced outputs. We find again the increasing (harmonic) distortion from 5kHz but staying below -102dBr at 20kHz (RCA) and -104dBr (balanced). This means the Topping noise shaper rejects most of noise beyond 90kHz, which is very nice. And actually, let me show you that:
You can see the rise of the noise just before 100kHz, and it is the same with all filters, as it is independent from them. That's related to the noise shaper of the delta-sigma modulator.
----
I nearly forgot the Jitter Test:
Very low level side bands, this is very good. The low level signal is somewhat buried into noise, and we'll see later that this comes from a combination of the DSP(?) in the digital path and the conversion + analog noise.
----
And now let's have a look at other less usual measurements. The one that I like is the resistance to intersample-overs.
This test is performed with dedicated test tones with a specific phase shift to generate a digital overs. If anything is in the digital path (oversampling filter /DSP / ASRC) and does not have enough headroom for digital overs, it will generate clipping within the interpolator. Here are the results (THD+N measurement up to 90kHz):
The Topping has 1dB headroom with volume set to 0dB (maximum). But at -2.5dB volume, we get the best results I ever measured. This is, I guess, because the Topping uses a DSP (more on that later) that plays the role of volume control too. So, if you use this one as a DAC, I really recommend reducing the volume that way, since so many master are too hot. The penalty on SINAD is acceptable since it is so good.
----
Other measurements (not shown):
The dynamic range is an excellent 122dB (CCIR-2K weighted), and even more so that the SNR is also an excellent 122dB (unweigthed) at full scale, indicating a well behaved/silent DAC accros the full range whatever is the output level.
Cross talk is negligible.
The pitch error is increasing with temperature, stabilising after 2 hours. The value is reasonable low at -10ppm, nothing you can hear. But we'll be back to that one when talking digital input...
I must say I was nothing else but impressed by the above results. Let's hope we get the same good results from headphones outputs.
Topping DX1 II - Measurements - Optical input to line level output
Basically, using the Optical input showed exactly the same performances. I did all my test using the SMSL PO100 Pro to feed the Topping. I had no issue.
So, although I repeated the same measurements, I don't publish any. This review is already long enough.
EDIT: And Topping solved the issue we suffered from digital input that was dropping, notably from CD players. It’s all good now. END EDIT
Topping DX1 II - Measurements - Optical input to optical output
I need to accelerate this very long review, but I had to investigate a little more the issue with optical input and also wanted to verify if that one is "bit perfect".
There is a menu to select "Optical Compatibility" with two undocumented options. Per my testing:
With d-1 selected, digital output to input does not appear bit perfect (997Hz test tone @0dBFS):
And it is no longer is at 0dBFS when getting out of the Topping. There's also some low level distortion and the noise floor is roughly 1bit more that what it should.
When selecting option d-2, things improve:
I overlaid the result with a WAV file processed by the software directly. The differences are run to run, nothing more. This time we get "perfect" digital output from the input. And it there is and ASRC in the digital, it is obviously transparent enough not to impact the 24bits PCM.
And quick look at the intersample over, 11025Hz @0dBFS with phase shift of 45°, that should generate an over of +3.01dB, again option d-2. I tested at full volume, and volume down by -3.5dB:
We get the over, but even better since volume control is active on digital output. See the right test, the digital volume is effectively down, meaning that you can get rid of overs for use with external DAC that would not appreciate them. This is first time I see that and this is very coooool!
Activating or not the PEQ does not change anything to the above, which I think is good news too, don't be afraid of using it. And see next post where I played with it.
Let me share a last one, the jitter test (at 44.1kHz):
This is perfect trace, and you're not used to see it that clean because most of the "stresser" signal is largely buried into analog noise floor.
And for the fun of it, let me share the multitone test in digital domain:
This is what this test looks like in "perfect" digital domain. Appreciate the vertical scale, and doing the maths like Amir does on this test, it means more than 27bits of distortion-free range
Topping DX1 II - Measurements - USB input to optical output
I tested the Topping DX1 II as a DDC and indeed I can send digital signal output from the computer.
From what I could test, it seems bit Perfect, but I did not spend much time testing, although my intersample-over test 5512.50Hz @0dBFS (from 16bits WAV source), with phase shift of 67.5° that should generate an over of +0.69dB, is indeed reproduced unchanged:
I get the over and no distortion, meaning no tangible change to the signal.
In addition, volume control is available on that digital output, and when activating it (menu U-2), I don't see a change. That said, look at the very interesting result below, when decreasing the volume by -2.5dB, I get exactly at 0.69dB + -2.5dB = -1.81dB:
And that means you can use this mechanism to get rid of intersample-overs issues from your collection. This is 16bits singal, ok, but appreciate there's no impact on the resolution. Similar to the optical input, I think this is really cool.
Topping DX1 II - Measurements - Headphones
Besides the output level that is 6dB higher, I got the same excellent results and this time the balanced output did not suffer PS leakage.
This is 1kHz @0dBFS, full power (8Vrms output) from balanced output:
This means a SINAD of 122.8dB! With volume down by 6dB, we get 119dB SINAD, still really excellent.
In low gain mode, the SINAD is a lower 118dB, but still excellent.
And these excellent results repeat with unbalanced headphone output, see:
This is a SINAD of 122.6dB! In low gain mode (0.8Vrms maximum output), it reduces to 117.4dB.
Last and not least, at 50mVrms output, in low gain mode, I get an SNR of 95.1dB:
This is into 100kΩ but I think Amir runs this one at 300Ω. I can do that, but another day, it is apero time for me, sorry
Conclusion
The Topping did very well on the bench. The issue I initially had with rear balanced output magically disappeared, and is now back
I have significant power supply leakage from XLR rear that I can’t get rid of. Weird.
@TOPPING @TOPPING-Service,I hope you can fix the issue with optical input. Thanks for the fix guys! Remains only some problems for you to fix, as clicking noise (RCA) when switching sampling rate and heavy distorsion that some are experiencing. Firmware V2.69 fixed issues with optical input, but obviously not all of them are solved yet.
Edit (15/07/2026): firmware 2.86 should fix all the above. Thanks @Bleib for the follow up. End Edit.
The bridge function of optical input to optical output, adding volume control and allowing to suppress any issue with intersample overs is really cool.
Please have a look and the following post below, I added several complementary tests. Notably, I measured the best results ever from a CD Player. This DAC makes any CD Player totally transparent. You’ll get to know more about the EQ function, it is very well implemented with minimum impact on the very high resolution of the Topping.
Once Topping has fixed all hardware issues, this little device will be a killer choice.
Enjoy the WE!
Flo
This is a review and measurements of the Topping DX1 II Dac and headphone amplifier.
I bought it from Topping site and received it rapidly. I got it for around 120$.
Topping DX1 II - Presentation
This little device acts as a DAC (USB or Optical input), with line level RCA/Balanced(mini TRS) output, and headphones amplifier (balanced and unbalanced outputs). On top, there is a digital pass-through (optical input to optical output) to chain these items and/or feed another DAC/Device. Last, and not least, we get PEQ (3 presets can be recorded).
Front knob is digital volume acting prior to conversion, and in fact even before the digital filter (I tested) at very precise steps as indicated on the front display.
The back of the unit is busy:
We have RCA and 4.4mm Balanced output, a digital input and a much less common digital output.
Inside we get high resolution ES9039Q2M DAC, and high power amplification.
User Experience
It was easy to configure the Topping with my Windows 11 computer since I had nothing to do
The operating system saw the Topping and named it "DX1 II". Interestingly, it sees it as an input too, and I was hoping I could get the optical input to feed my computer, but no. The digital output will
The menu offers several possibilities to tune the device, High/Low Gain, Front/Rear outputs activation, digital filter selection, and few others, one of which one is a setting for Optical input compatibility which had no effect on my side (see the review).
Measurements
All measurements performed with an E1DA Cosmos ADCiso (grade 0) in mono mode, the Cosmos Scaler (100kohms from unbalanced input) and APU (when required) for analog outputs, and a Motu UltraLite Mk5 for digital.
This review was performed with the firmware V2.69.
Topping DX1 II - Measurements - USB input to line level output
From Rear connectors (into 100kΩ and 200kΩ), I measured:
- 2.310Vrms left channel (SE), 2,309Vrms right channel from USB input, that's a low 0.01dB channel imbalance, very good.
- 4.948Vrms from Balanced left and 4.952Vrms from right one, again 0.01dB channel imbalance.
- 816mVrms from left unbalanced in low gain mode, and 4.001Vrms in high gain mode, with right channel playing 0.02dB higher, very good too.
- 1.588Vrms from left balanced in low gain mode, and 7.78Vrms in high gain mode, again same low 0.02dB channel imbalance.
Let's start measurements with USB to rear RCA outputs.
The below is the standard dashboard, 1kHz @0dBFS, volume down to -0.5dB so the output is 2.1Vrms as to align with @Amir's measurement of the same. And I aligned the SINAD (or THD+N) calculation to the regular span of Amir, that is 10Hz to 22.4kHz:
Impressive results for unbalanced output. This is the right channel, at 120.8dB SINAD, and left one is the exact same. It brings this little device at the top of the excellent performers, nice!
When increasing to full 2.3Vrms output, the SINAD is 121dB.
EDIT: I initially had an issue with rear balanced output, with lots of Power Supply leakage, and after leaving the device on for many hours, it is all gone. So here is the view at full output voltage (5Vrms):
This is a SINAD of 123.3dB.
At 4Vrms output (vol at -1.5dB), I get a SINAD of 122.7dB average between the two channels (122.8dB R and 122.6dB L). This is SOTA performance!
END EDIT
-----
Let's go back to to RCA output. The very good results with 1kHz sine tone continue with multitone:
We get roughly 21+ to 23 bits of distortion-free range, again excellent! That said, note an obvious increase of distortion at higher frequencies, but still bellow -125dBr!
And note that in balanced mode, the MT is a little better, although that won't make a difference to your ears:
That is true best in class (ignore the spike at 150Hz, I get it sometimes, it's from my testing gears).
----
Next is the bandwidth and options for oversampling filters (8 of them!), as shown below:
Actually, this is exactly the same as the Topping D50III and I share the recommendation of @amirm on that one: Go filter 3, it offers the best attenuation, least ringing and audio bandwidth is protected (fully flat).
----
To keep going with the standard reviews of Amir, let's have a look at THD+N vs frequency with a bandwidth extended to 90kHz to include distorsion and noise, and that is a rough test:
Excellent results here, best in class if you allow me, especially with unbalanced outputs. We find again the increasing (harmonic) distortion from 5kHz but staying below -102dBr at 20kHz (RCA) and -104dBr (balanced). This means the Topping noise shaper rejects most of noise beyond 90kHz, which is very nice. And actually, let me show you that:
You can see the rise of the noise just before 100kHz, and it is the same with all filters, as it is independent from them. That's related to the noise shaper of the delta-sigma modulator.
----
I nearly forgot the Jitter Test:
Very low level side bands, this is very good. The low level signal is somewhat buried into noise, and we'll see later that this comes from a combination of the DSP(?) in the digital path and the conversion + analog noise.
----
And now let's have a look at other less usual measurements. The one that I like is the resistance to intersample-overs.
This test is performed with dedicated test tones with a specific phase shift to generate a digital overs. If anything is in the digital path (oversampling filter /DSP / ASRC) and does not have enough headroom for digital overs, it will generate clipping within the interpolator. Here are the results (THD+N measurement up to 90kHz):
| Intersample-overs tests Bandwidth of the THD+N measurements is 20Hz - 90kHz | 5512.5 Hz sine, Peak = +0.69dBFS | 7350 Hz sine, Peak = +1.25dBFS | 11025 Hz sine, Peak = +3.0dBFS |
| Topping DX1 II (vol 0dB) | -111dB | -16dB | -16dB |
| Topping DX1 II (vol -2.5dB) | -111dB | -109.3dB | -105.7dB |
The Topping has 1dB headroom with volume set to 0dB (maximum). But at -2.5dB volume, we get the best results I ever measured. This is, I guess, because the Topping uses a DSP (more on that later) that plays the role of volume control too. So, if you use this one as a DAC, I really recommend reducing the volume that way, since so many master are too hot. The penalty on SINAD is acceptable since it is so good.
----
Other measurements (not shown):
- IMD AES-17 DFD "Analog" (18kHz & 20kHz 1:1) : -111.4dB
- IMD AES-17 DFD "Digital" (17'987Hz & 19'997Hz 1:1) : -111.6dB
- IMD AES-17 MD (41Hz & 7993Hz 4:1): -111.6dB
- IMD DIN (250Hz & 8kHz 4:1) : -111.6dB
- IMD CCIF (19kHz & 20kHz 1:1) : -111.3B
- IMD SMPTE (60Hz & 17kHz 1:4) : -111.6dB
- IMD TDFD Bass (41Hz & 89Hz 1:1) : -111.2dB
- IMD TDFD (13'58Hz & 19841Hz 1:1) : -111.4dB
- Dynamic Range : 122dB (CCIR-2k weighted with dither @-60dBFS)
- Crosstalk: -133dBr (1kHz)
- Pitch Error (GPSDO corrected) : 19'996.80Hz (19'997Hz requested) ie -10ppm
The dynamic range is an excellent 122dB (CCIR-2K weighted), and even more so that the SNR is also an excellent 122dB (unweigthed) at full scale, indicating a well behaved/silent DAC accros the full range whatever is the output level.
Cross talk is negligible.
The pitch error is increasing with temperature, stabilising after 2 hours. The value is reasonable low at -10ppm, nothing you can hear. But we'll be back to that one when talking digital input...
I must say I was nothing else but impressed by the above results. Let's hope we get the same good results from headphones outputs.
Topping DX1 II - Measurements - Optical input to line level output
Basically, using the Optical input showed exactly the same performances. I did all my test using the SMSL PO100 Pro to feed the Topping. I had no issue.
So, although I repeated the same measurements, I don't publish any. This review is already long enough.
EDIT: And Topping solved the issue we suffered from digital input that was dropping, notably from CD players. It’s all good now. END EDIT
Topping DX1 II - Measurements - Optical input to optical output
I need to accelerate this very long review, but I had to investigate a little more the issue with optical input and also wanted to verify if that one is "bit perfect".
There is a menu to select "Optical Compatibility" with two undocumented options. Per my testing:
- option d-1 synchronizes to the incoming signal (with embedded clock)
- option d-2 re-synchronises the incoming signal, probably via an ASRC.
With d-1 selected, digital output to input does not appear bit perfect (997Hz test tone @0dBFS):
And it is no longer is at 0dBFS when getting out of the Topping. There's also some low level distortion and the noise floor is roughly 1bit more that what it should.
When selecting option d-2, things improve:
I overlaid the result with a WAV file processed by the software directly. The differences are run to run, nothing more. This time we get "perfect" digital output from the input. And it there is and ASRC in the digital, it is obviously transparent enough not to impact the 24bits PCM.
And quick look at the intersample over, 11025Hz @0dBFS with phase shift of 45°, that should generate an over of +3.01dB, again option d-2. I tested at full volume, and volume down by -3.5dB:
We get the over, but even better since volume control is active on digital output. See the right test, the digital volume is effectively down, meaning that you can get rid of overs for use with external DAC that would not appreciate them. This is first time I see that and this is very coooool!
Activating or not the PEQ does not change anything to the above, which I think is good news too, don't be afraid of using it. And see next post where I played with it.
Let me share a last one, the jitter test (at 44.1kHz):
This is perfect trace, and you're not used to see it that clean because most of the "stresser" signal is largely buried into analog noise floor.
And for the fun of it, let me share the multitone test in digital domain:
This is what this test looks like in "perfect" digital domain. Appreciate the vertical scale, and doing the maths like Amir does on this test, it means more than 27bits of distortion-free range
Topping DX1 II - Measurements - USB input to optical output
I tested the Topping DX1 II as a DDC and indeed I can send digital signal output from the computer.
From what I could test, it seems bit Perfect, but I did not spend much time testing, although my intersample-over test 5512.50Hz @0dBFS (from 16bits WAV source), with phase shift of 67.5° that should generate an over of +0.69dB, is indeed reproduced unchanged:
I get the over and no distortion, meaning no tangible change to the signal.
In addition, volume control is available on that digital output, and when activating it (menu U-2), I don't see a change. That said, look at the very interesting result below, when decreasing the volume by -2.5dB, I get exactly at 0.69dB + -2.5dB = -1.81dB:
And that means you can use this mechanism to get rid of intersample-overs issues from your collection. This is 16bits singal, ok, but appreciate there's no impact on the resolution. Similar to the optical input, I think this is really cool.
Topping DX1 II - Measurements - Headphones
Besides the output level that is 6dB higher, I got the same excellent results and this time the balanced output did not suffer PS leakage.
This is 1kHz @0dBFS, full power (8Vrms output) from balanced output:
This means a SINAD of 122.8dB! With volume down by 6dB, we get 119dB SINAD, still really excellent.
In low gain mode, the SINAD is a lower 118dB, but still excellent.
And these excellent results repeat with unbalanced headphone output, see:
This is a SINAD of 122.6dB! In low gain mode (0.8Vrms maximum output), it reduces to 117.4dB.
Last and not least, at 50mVrms output, in low gain mode, I get an SNR of 95.1dB:
This is into 100kΩ but I think Amir runs this one at 300Ω. I can do that, but another day, it is apero time for me, sorry
Conclusion
The Topping did very well on the bench. The issue I initially had with rear balanced output magically disappeared, and is now back
I have significant power supply leakage from XLR rear that I can’t get rid of. Weird.@TOPPING @TOPPING-Service,
Edit (15/07/2026): firmware 2.86 should fix all the above. Thanks @Bleib for the follow up. End Edit.
The bridge function of optical input to optical output, adding volume control and allowing to suppress any issue with intersample overs is really cool.
Please have a look and the following post below, I added several complementary tests. Notably, I measured the best results ever from a CD Player. This DAC makes any CD Player totally transparent. You’ll get to know more about the EQ function, it is very well implemented with minimum impact on the very high resolution of the Topping.
Once Topping has fixed all hardware issues, this little device will be a killer choice.
Enjoy the WE!
Flo
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