Review and Measurements of Topping DX3Pro DAC and Headphone Amp

[Noob2313]

Do you see any limitations in using this as a preamp too, in terms of the volume control being digital?

Not a problem at all. It works great as a preamp.

In v2, you can either use option "d-0" to enable volume control (the default) or you can use option "d-1" to disable volume control and provide a full (unattenuated) "line out" signal to the outputs. (Go here for more details on these setup options.)

If your external amplifier has volume control, you can use either option. My desktop amp is a Topping PA3. I use the volume control on the PA3 for coarse adjustments and the (stepped) volume control on the DX3 Pro for fine adjustments (see photo). It's an "impure" hybrid solution, but it's working well for me. I'm a pragmatist.

If your external amp does not have volume control, then obviously you'll need to use the DX3 Pro for that function. But, worry not. It's a good implementation. No complaints from me about that.

 

[Noob2313]

I received my FOURTH copy of the DX3 Pro today (my second copy of V2).

Please say a prayer that my insanity will finally end. One way or the other... LOL

Arghh! Topping has slipstreamed another change.

I must admit to being thoroughly UNIMPRESSED with their engineering process. If change management is this loosey-goosey, then they're just winging it on everything else too...

The good news is that all they changed this time was the remote control.

The bad news is that the old remote was one of my all-time favorites. It had the PERFECT hand shape and feel. Fortunately, I've still got an old one left over from one of my dead DX3 Pros and they seem to work interchangeably.

Here are photos comparing the new and old remotes. The new one is on the left.

The biggest change is that the new remote ("RC-15A") uses two AAA batteries, whereas the old one ("RC-15") used one CR-2032 battery (in a delightfully quirky and unique spring holder). For me, I'd much rather have the Li button cell because over time alkaline cells always leak and ruin the device.

In order to fit the thicker battery they had to change the shape. Gone is the heavenly rounded cross-section of the old remote. The new one has sharp edges that don't feel nice at all. The weight (with batteries) also increased substantially: 58 g vs 36 g.

Sigh!!!

 

[o2so]

Not a problem at all. It works great as a preamp.

In v2, you can either use option "d-0" to enable volume control (the default) or you can use option "d-1" to disable volume control and provide a full (unattenuated) "line out" signal to the outputs. (Go here for more details on these setup options.)

If your external amplifier has volume control, you can use either option. My desktop amp is a Topping PA3. I use the volume control on the PA3 for coarse adjustments and the (stepped) volume control on the DX3 Pro for fine adjustments (see photo). It's an "impure" hybrid solution, but it's working well for me. I'm a pragmatist.

If your external amp does not have volume control, then obviously you'll need to use the DX3 Pro for that function. But, worry not. It's a good implementation. No complaints from me about that.

Thanks for sharing your experience, much appreciated.

If possible I was also after a more technical comment on the following:
- is this DAC controlling the volume in the digital domain when used as a preamp
- if yes, is there any evidence that this will degrade sound to a potentially audible extent, when used at low volumes.

Thanks!

 

[gazzawazza]

2) Buy a Topping DX3 Pro (V2), with worse headphone sound quality, but taking less risk to have some problems with the DAC.

hi

why is there worse sound quality?


thanks,

Gary

 

[gazzawazza]

Rule of a thumb is output impedance of amplifier should be 1/8 of headphones impedance, v2 is advertised as <10Ohm, so to simplify it will not make a difference for all headphones with impedance over 80Ohm. For headphones with impedance lower than that, it might affect frequency response or in extreme cases introduce some hiss (happens on ultra sensitive armatures).
This is very simplified however, since it depends on specific headphones, for instance planar headphones are not subject to this despite very low impedance.

Hi Yuno

Could you help me over this too?

I was about to buy the dx3 pro v2.

However, I am concerned about your posts (and others) saying that the v2 is causing sound quality issues.

Could you explain what the problem is?

Is there any way to deal with the problem?

My headphones are currently:

sennheiser hd599 (50 ohm)
sennheiser jubilee hd58x (150 ohm)



thanks for any help,

Gary

 

[Yuno]

Hi Yuno

Could you help me over this too?

I was about to buy the dx3 pro v2.

However, I am concerned about your posts (and others) saying that the v2 is causing sound quality issues.

Could you explain what the problem is?

Is there any way to deal with the problem?

My headphones are currently:

sennheiser hd599 (50 ohm)
sennheiser jubilee hd58x (150 ohm)



thanks for any help,

Gary

The problem is that output impedance of amplifier which was originally <1Ohm for v1 is now listed as sub <10Ohm for v2. This is not a good thing and might add some distortion when using headphones with impedance lower than 80Ohm. Solution: not using built in amplifier, or using high impedance headphones.
Whether this is a large issue or not is up for you to decide. Just to clarify, I don't own v2 and even if I did I'm sure with my setup I would not be able to tell the difference between v2 and v1, but from the perspective of audio engineering going from 1 to 10Ohm on amplifier output impedance is a downgrade. This is why some people prefer v1.
Until we get tests on v2, everything is just guessing. <10Ohm might very well mean 2 or 3Ohm, which would be completely acceptable.

 

[gazzawazza]

The problem is that output impedance of amplifier which was originally <1Ohm for v1 is now listed as sub <10Ohm for v2. This is not a good thing and might add some distortion when using headphones with impedance lower than 80Ohm. Solution: not using built in amplifier, or using high impedance headphones.
Whether this is a large issue or not is up for you to decide. Just to clarify, I don't own v2 and even if I did I'm sure with my setup I would not be able to tell the difference between v2 and v1, but from the perspective of audio engineering going from 1 to 10Ohm on amplifier output impedance is a downgrade. This is why some people prefer v1.
Until we get tests on v2, everything is just guessing. <10Ohm might very well mean 2 or 3Ohm, which would be completely acceptable.

very kind of you to explain. ty.

One thing I noticed on the Topping website is a power output difference between the dx3 pro and the LDAC version (former is 1000mw, latter is 700mw).

1000mW -http://www.tpdz.net/products_detail/productId=39.html

700mW (LDAC) - http://www.tpdz.net/products_detail/productId=43.html

Assuming the data is current, perhaps i am safer going for the LDAC? Or have i got that the wrong way round? LDAC is 100 ohm output impedance.



thanks,

Gary

 

[Yuno]

Assuming the data is current, perhaps i am safer going for the LDAC? Or have i got that the wrong way round? LDAC is 100 ohm output impedance.

RCA output is 100Ohm impedance and it's the same for v1 and v2, headphone output is <10Ohm. It's up to you, v2 has higher output impedance and less power (700 instead of 1000mW), v1 has better specs, but is known to be unreliable and even potentially dangerous for headphones, which is why topping reworked amplifier for v2.
I would personally stay away from v1, topping changed design for a reason, I myself had to send my unit back to China due to it being faulty. You can take a risk and buy v2 which we know nothing about because Amir only tested v1, or you can get v1 and hope you get lucky with your unit. Quite a few people here have v1 with no problems, so as long as you get lucky it's fine I guess.
Frankly I would not recommend buying dx3 pro at all until v2 gets tested.

 

[2ko]

Hi Yuno

Could you help me over this too?

I was about to buy the dx3 pro v2.

However, I am concerned about your posts (and others) saying that the v2 is causing sound quality issues.

Could you explain what the problem is?

Is there any way to deal with the problem?

My headphones are currently:

sennheiser hd599 (50 ohm)
sennheiser jubilee hd58x (150 ohm)



thanks for any help,

Gary

I am currently using DX3 Pro V2 with Jubilee HD58x. Just only one thing making me confused is I don't why I have to turn the volume all the way up to -26db to get a good sound. I'm not sure is that normal but other than that there is no issue for me.

 

[noel_fs]

I am currently using DX3 Pro V2 with Jubilee HD58x. Just only one thing making me confused is I don't why I have to turn the volume all the way up to -26db to get a good sound. I'm not sure is that normal but other than that there is no issue for me.

-26db is low volume specially if you are using low gain then its really really low volume. Db is not the same as percentage, 45% in windows equals to -12.5db. So you do the math

 

[gazzawazza]

RCA output is 100Ohm impedance and it's the same for v1 and v2, headphone output is <10Ohm. It's up to you, v2 has higher output impedance and less power (700 instead of 1000mW), v1 has better specs, but is known to be unreliable and even potentially dangerous for headphones, which is why topping reworked amplifier for v2.
I would personally stay away from v1, topping changed design for a reason, I myself had to send my unit back to China due to it being faulty. You can take a risk and buy v2 which we know nothing about because Amir only tested v1, or you can get v1 and hope you get lucky with your unit. Quite a few people here have v1 with no problems, so as long as you get lucky it's fine I guess.
Frankly I would not recommend buying dx3 pro at all until v2 gets tested.

I'm extremely grateful for your explanation and advice.

Many thanks.

I was checking the specs again and noticed that the newer version (LDAC) is in fact <10 ohm impedance, not 100, at the headphone output.

Yes, the older version was <1 ohm

Just mentioning this to correct what i said earlier.


cheers,

Gary

 

[heyagod]

@TP-Wong Hi, can you send a LDAC/V2 version of DX3 Pro for @amirm to review? The changes to the headphone amp need to be looked at, since there is a big jump in output impedance (from <1 to 10ohms), which affects its usability with low impedance headphone/IEMs

 

[dcolak]

I don´t know if someone already mentioned this but, if you change the bitrate, same dB shown on the panel will produce different volume at the headphone output.

If you use 32bit float output and -36dB at DX3PRO it will be much lower volume than using 16bit integer output and same -36dB at DX3PRO.

Same goes with 16bit vs 24bit.

Maybe that explains why different people have different volume with same dB shown on DX3Pro

 

[dkinric]

That's interesting, dcolak, and welcome to ASR!
I was an early adopter of this unit and was not impressed with the loudness, wheras others said it blew their ears off at lower volume settings than I was using (def was on high gain) with similar cans.
What should this bitrate be set for under which conditions? Is it a max bitrate setting?

 

[noel_fs]

I don´t know if someone already mentioned this but, if you change the bitrate, same dB shown on the panel will produce different volume at the headphone output.

If you use 32bit float output and -36dB at DX3PRO it will be much lower volume than using 16bit integer output and same -36dB at DX3PRO.

Same goes with 16bit vs 24bit.

Maybe that explains why different people have different volume with same dB shown on DX3Pro

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[Veri]

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...

He is saying, that if your device or OS is outputting 16 bits, 24 bits or 32 bits, this will affect the digital volume control final volume.
Depending on people's phones, computer or other devices, one person's "-6dB" is different from another's "-6dB" on DX3.

 

[dkinric]

Oh, I thought he was referring to a bitrate setting on the DX3PRO that would affect loudness. I pass native bitrate via Roon, so this would vary according to recording.

 

[noel_fs]

...

He is saying, that if your device or OS is outputting 16 bits, 24 bits or 32 bits, this will affect the digital volume control final volume.
Depending on people's phones, computer or other devices, one person's "-6dB" is different from another's "-6dB" on DX3.

hes not saying that

 

[noel_fs]

do not change bit depth from 32bit, it will affect quality when using volume which is always. And the volume is going to be the same.

 

[Veri]

hes not saying that

He's saying exactly that:
If you use 32bit float output and -36dB at DX3PRO it will be much lower volume than using 16bit integer output and same -36dB at DX3PRO.

do not change bit depth from 32bit, its will affect quality when using volume which is always. And the volume is going to be the same.

It will affect quality when using volume which is always?? How so, what's the mechanism or cause here? Any substance behind that statement?

Oh, I thought he was referring to a bitrate setting on the DX3PRO that would affect loudness. I pass native bitrate via Roon, so this would vary according to recording.

There is no bitrate setting on the DX3, only on the source device.