Topping A90 Headphone Amplifier Review

[Beppe]

In the end, since I found no answer in the comparison with Shiit Jotunheim , i could not resist and i decided to buy the Topping A90.
It arrived 2 days ago.
I connected it to the Chord Qutest connected to the PC with USB and I can confirm that there are no noises of any kind at any volume in the balanced XLR and 4.4 outputs and not even in the single ended output.
So I tried the Topping for a short time, but the first impressions are that the A90 compared to the Shiit Jotunheim sounds much cleaner and more transparent, I would say even more three-dimensional with a wider soundstage. I wait to see how it will go after a few hours of running in to judge better.
But already now I can say that there is already an important improvement in the quality of listening compared to Shiit.
Trying the HD660S it looks like another headset than before with a detail and a soundstage of greater impact than before. The same feeling also trying other headphones like the HD800S, the Grado GS1000, and also the DT 1990 Pro.
Then trying the top-level handmade headphones like the Italian "Spirit Torino Twin Pulse Isobaric System" the sound is crystal clear, very detailed, almost like attending a live performance.Of course the Spirit Torino headphones sounded this way even before but with the A90 it has improved even more.

 

[Rigel]

If someone can find it interesting, I have started to measure the leakage currents of each of the components, individually connected or not and according to whether the idefender is connected.

Leakage current in the amplifier with the idefender connected. They are not static values, the PC generates leakage currents depending on the processing. Booting the PC, player etc. Through the neutral and phase conductors, noise is also transmitted.

Leakage current in the amplifier without the idefender connected. It is common that instead of being downloaded with the PC socket, part is transmitted through the ground of the amplifier through RCA and USB cables.

Leakage current from the computer with the idefender connected. By limiting the connection to the rest of the system, the leakage current tends to be discharged by its own ground. When connected, the current stabilizes and when disconnected, it varies in bursts according to the PC processing.

DAC leakage current.

The USB cable without the shield connected from the manufacturer Valab, and with own external power connection. Noise is also transmitted.

 

[Rigel]

In the end, since I found no answer in the comparison with Shiit Jotunheim , i could not resist and i decided to buy the Topping A90.
It arrived 2 days ago.
I connected it to the Chord Qutest connected to the PC with USB and I can confirm that there are no noises of any kind at any volume in the balanced XLR and 4.4 outputs and not even in the single ended output.
So I tried the Topping for a short time, but the first impressions are that the A90 compared to the Shiit Jotunheim sounds much cleaner and more transparent, I would say even more three-dimensional with a wider soundstage. I wait to see how it will go after a few hours of running in to judge better.
But already now I can say that there is already an important improvement in the quality of listening compared to Shiit.
Trying the HD660S it looks like another headset than before with a detail and a soundstage of greater impact than before. The same feeling also trying other headphones like the HD800S, the Grado GS1000, and also the DT 1990 Pro.
Then trying the top-level handmade headphones like the Italian "Spirit Torino Twin Pulse Isobaric System" the sound is crystal clear, very detailed, almost like attending a live performance.Of course the Spirit Torino headphones sounded this way even before but with the A90 it has improved even more.

I'm glad it doesn't have noise issues, it's a good amp. I also have the SP200 and I haven't used it in a long time. With the HD800, transparency is complete.

 

[Audimon]

If someone can find it interesting, I have started to measure the leakage currents of each of the components, individually connected or not and according to whether the idefender is connected.

Leakage current in the amplifier with the idefender connected. They are not static values, the PC generates leakage currents depending on the processing. Booting the PC, player etc. Through the neutral and phase conductors, noise is also transmitted.

View attachment 75265

Leakage current in the amplifier without the idefender connected. It is common that instead of being downloaded with the PC socket, part is transmitted through the ground of the amplifier through RCA and USB cables.

View attachment 75267


Leakage current from the computer with the idefender connected. By limiting the connection to the rest of the system, the leakage current tends to be discharged by its own ground. When connected, the current stabilizes and when disconnected, it varies in bursts according to the PC processing.

View attachment 75268

View attachment 75278



DAC leakage current.

View attachment 75272

View attachment 75273


The USB cable without the shield connected from the manufacturer Valab, and with own external power connection. Noise is also transmitted.

View attachment 75275

Why all these unshielded wires?

 

[Rigel]

Hi Audiomon.

I made those cables to make measurements when I measure a component so they don't have the cover. They must be uncovered and separated from each other so that the current clamp can make the measurements on each cable. If not, it would measure the mix between them together and values could be overridden.
The electric current generates a magnetic field that is measured by the induction clamp on a coil.
This is a specific model to measure leakage currents, they usually have very low values compared to normal power consumption values.

 

[Racheski]

If someone can find it interesting, I have started to measure the leakage currents of each of the components, individually connected or not and according to whether the idefender is connected.

Leakage current in the amplifier with the idefender connected. They are not static values, the PC generates leakage currents depending on the processing. Booting the PC, player etc. Through the neutral and phase conductors, noise is also transmitted.

View attachment 75265

Leakage current in the amplifier without the idefender connected. It is common that instead of being downloaded with the PC socket, part is transmitted through the ground of the amplifier through RCA and USB cables.

View attachment 75267


Leakage current from the computer with the idefender connected. By limiting the connection to the rest of the system, the leakage current tends to be discharged by its own ground. When connected, the current stabilizes and when disconnected, it varies in bursts according to the PC processing.

View attachment 75268

View attachment 75278



DAC leakage current.

View attachment 75272

View attachment 75273


The USB cable without the shield connected from the manufacturer Valab, and with own external power connection. Noise is also transmitted.

View attachment 75275

So in conclusion the i defender works as designed?

 

[robertozappala]

Like this:

https://www.amazon.it/Mogami-2534-C...uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

@JohnYang1997 Johnnnnnnn

 

[ra990]

I can vouch for the iDefender and the iGalvanic working well and taking care of ground hum/loop issues and in the case of iGalvanic, even some timing jitter issues I had with more sensitive DACs. I have used them with success on various setups through the years. These products don't magically make an already working setup better. That's what they seem to advertise and that's why they have a bad reputation. But the fact is, when you actually have an issue, like a ground hum, they work as they claim and improve the situation. Only buy them if you have issues, otherwise you're wasting your money.

 

[EdW]

I can vouch for the iDefender and the iGalvanic working well and taking care of ground hum/loop issues and in the case of iGalvanic, even some timing jitter issues I had with more sensitive DACs. I have used them with success on various setups through the years. These products don't magically make an already working setup better. That's what they seem to advertise and that's why they have a bad reputation. But the fact is, when you actually have an issue, like a ground hum, they work as they claim and improve the situation. Only buy them if you have issues, otherwise you're wasting your money.

The products mentioned above can materially help but this interference has always been a bit of a bogeyman since it can panic people to visit the snake oil salesmen who will say that scientific analysis can always leave an immeasurable, but nevertheless allegedly subtly audible, aberration and they now need to spend many k$. The usual products such as special mains filtering, USB bridges in very pretty cases and, of course, special cables. ASR has frequently debunked most of these but a couple of articles by Archimago also may be of interest:

http://archimago.blogspot.com/2015/05/measurements-corning-usb-3-optical.html

http://archimago.blogspot.com/2015/05/measurements-usb-hubs-and-8khz-phy.html

Of course it is a lot harder to track these issues down without ‘scopes, spectrum analysers and APX555s!

 

[Rigel]

So in conclusion the i defender works as designed?

Hi Racheski

It is as Ra990 comments. The noise will decrease, as long as the cause of the noise is the leakage current coming from the PC through the USB connection.
If the cause is other equipment, it could even make it worse, because it depends a lot on the installation and the idefender only limits the leakage current of the PC.

If the cause is the PC, you should hear a noise similar to the video that I posted.

I have quite a few USB conditioners, some of the more expensive like the ifi micro 3.0 and currently I only have the idefender connected, because with the D90 + A90, it is not necessary anymore and not even the idefender is essential because I normally use balanced connections and not RCA.

In my system and listening to music, I am not able to appreciate the difference from having the idefender to not having it even with the RCA connections and even less with the XLR.

At least to my ear, because I don't have any major leakage problems or I just can't hear the difference.

Those who do have noise problems in normal listening conditions, if it could be advisable.

 

[Rigel]

The products mentioned above can materially help but this interference has always been a bit of a bogeyman since it can panic people to visit the snake oil salesmen who will say that scientific analysis can always leave an immeasurable, but nevertheless allegedly subtly audible, aberration and they now need to spend many k$. The usual products such as special mains filtering, USB bridges in very pretty cases and, of course, special cables. ASR has frequently debunked most of these but a couple of articles by Archimago also may be of interest:

http://archimago.blogspot.com/2015/05/measurements-corning-usb-3-optical.html

http://archimago.blogspot.com/2015/05/measurements-usb-hubs-and-8khz-phy.html

Of course it is a lot harder to track these issues down without ‘scopes, spectrum analysers and APX555s!

hi EdW

I want to make an important clarification to clear doubts and sorry for going a bit off topic. I will not dwell further on the USB question.

One thing is data processing, jitter etc. And something else different from the leakage loops, that are being talked about and that I have simply demonstrated with an ammeter clamp, which is an audible and measurable echo.

 

[Veri]

@JohnYang1997 Johnnnnnnn

Why not send him a PM instead of shitting up the thread?

-You can use Topping A90 balanced output even with unbalanced inputs... " would a90 / d90 always work in balanced? " - yes
-Why not use the project kameleon with an unbalanced amp like upcoming L30? Using A90 with some unbalanced hardware EQ seems really counter-intuitive to me and I wouldn't recommend it. Why would you insert the kameleon between D90 and A90, fully balanced circuitry? I feel like you are harming performance and might end up with noise/ground issues. Consider digital EQ.

 

[robertozappala]

[QUOTE = "Veri, post: 467962, membro: 909"] Perché non inviargli un PM invece di perdere il thread?

Prendi in considerazione l'EQ digitale . [/ CITAZIONE]

Quale? Presto userò Audirvana con Mac, suggerimento?
Grazie Veri

ps non volevo disturbare John with PM

 

[iamwhoiam]

Having multiple earthed audio devices isn't a new phenomenon. Earth loops (and therefore hum) has existed since the invention of AC mains.

However, the A90 is predominantly designed for balanced usage.

Out of curiosity @JohnYang1997 - would the following solve everyone's issues?

 

[JohnYang1997]

Having multiple earthed audio devices isn't a new phenomenon. Earth loops (and therefore hum) has existed since the invention of AC mains.

However, the A90 is predominantly designed for balanced usage.

Out of curiosity @JohnYang1997 - would the following solve everyone's issues?

View attachment 75415

No.

 

[Ddd]

The noise in my setup comes up through the USB cable - if I disconnect the USB cable the noise stops, but there is a tone that emanates in H Gain mode with both XLR and RCA cable connected - in XLR mode switched on.

You don't mention what source is used with the D90, what is it?

Thanks for the details

Yes, it's normal to not be able to Zero out volume at the lowest setting, it is also variable via the drive from the D90 - so you could set the D90 in PRE mode and reduce the output until the A90 Zero Volume + L/M/H Gain has really zero audio output through your headphones / speakers.

There might be an adjustment for balance trim in the A90 / D90 that could get the L/R balance of volume the same so the Right and Left channel "go out" at Zero at the same time. My A90 in H Gain with D90 in PRE mode -00.0dB at Zero volume I still have sound in headphones, with Right side louder than Left side.

@JohnYang1997 - is there a channel balance trim in either the A90 / D90 we can adjust?

Yeah. If you connect both XLR and RCA interconnect both at the same time, even is Switched to XLR input on A90 the noise is still present. Use ONLY XLR interconnect

My source is My laptop to D90 MQA. Laptop doesn't have Ground issues due to it's own Internal battery i guess? Even when Charging the laptop theres no Earth connection due to the use of DC connector and Earth only present at its own LPS rectifier brick. Did not try with desktop PC.
But if you got noise from your desktop PC likely is due to ground loop from USB.
A iFi iDefender+ plug to your PC and your USB plug behind it and to your D90 will solve your problem. No external power needed for the iFi iDefender+ too. The iDefender+ is just there to break the loop for you by breaking the (USB ground) from PC leaving only the (USB Data +/-) and (USB Vcc) to go through for a Vbus handshake for the D90 XMOS USB Input chip so your PC can see the 'D90 connected" as recognition if i'm not wrong.

what differences are there between Idefender and isilencer?
Thank you
Roberto

iSilencer is there to clean and filter the noise of your USB port to give a cleaner power and signal to your connected device
iDefender is there to breaks the USB Ground to Break the Ground Loop connection between your DAC and your PC

What is the side entrance for?

External supply for USB. A phone charger should work.

The side entrance is to external supply power to the iDefender to its USB Vcc and at the same time forcefully Breaking the USB Ground
With a Clean external power supply like the iFi own iFi iPower 5V to supply the iDefender+ side entrance means those USB-Powered DAC like Topping D10s will benefit from a cleaner Power supply and a ground loop free connection

For desktop DAC like D90 that is "Self Powered" already (hope i did'nt confuse you), Means the side entrance external power input of iFi iDefender+ is not required. the iDefender+ will detects the ground loop automatically and break the USB Ground automatically .
That way your D90 should be free from PC Ground Loop issues after that.

I understand it from here last time, ignore the product, read only the technicals XD
https://www.head-fi.org/threads/ifi-audio-igalvanic3-0-the-holy-grail-of-audio.839638/

 

[iamwhoiam]

No.

Why is that? Is it not due to earth loops?

BTW - not criticising, just wondering what would be the technical solution

 

[Hi_Fil]

The problem could be the DT 1990 headphones, I read that it has a 3-pin mini-XLR connector instead of a 4-pin one, which would not allow it to be used on balanced amplifiers

 

[JohnYang1997]

Why is that? Is it not due to earth loops?

BTW - not criticising, just wondering what would be the technical solution

This method was tested ages ago. No hope. The capacitors and the diodes do not conduct. Basically equivalent to adding 10 ohm. No improvement. Higher value gives worse results.
A simple 'No.' was probably much more tham adequate.

 

[Audimon]

Ok, I finally got my A90. Will write up some details later but I have 1 big question for now.
I have it connected via xlr to adi2dac and I just have NO soundstage out of A90, not via Bal or SE.
From adi2dac I hear all the instruments separated, wide and every one in its place but when I switch to A90 they are all just a soup in the middle of my head. Much more so on Sundara being open back than on Z1R.
Not saying it is necessarily something to do with the A90, could be anything through to wall socket wiring. I don't know but maybe someone had similar experience with a dedicated headphone amp. What could be the reason?