Topping A90 Headphone Amplifier Review

[burma]

That's not really fair to say that. However it's understandable that regular people don't understand.

Firstly, you can go to Massdrop 789's page, check the specifications of that. You will see that balanced output is twice as noisy. So by showing this, it's not just A90 that has this property.

Now, if you have access to Douglas Self's small signal book(or doesn't matter if you don't), it's said that balance connection is inherently more noisy than single-ended. While this is not intuitive, it's actually true. If you have balanced to single ended or single ended to balanced conversion, you get even more noise(relatively). Balanced connection however have better rejection to interference.

At this moment, we established that this is common and not a strange phenomenon.

Then, in comparison, A90's balanced output, even though is relatively more noisy than single-ended output, has much less noise of single ended output on many amplifiers even compared with 789. 0.6uV vs 1.2uV. Single ended output of A90 is just lower at 0.2uV. Probably the lowest on the market, at least to my knowledge.

Lastly, does it matter. Maybe yes maybe no. Most of the headphones aren't noisy with over 4uV noise. Most sensitive IEMs can produce audible noise with 0.8uV noise. So it really depends. For the user, just try it. Pretty simple.

Sorry - my words came out wrong. I didn't mean Topping in particular, but in general. Makes sense, now that it's been explained. I will have to see if I can notice it once my XLR headphone cable arrives.

 

[JohnYang1997]

Sorry - my words came out wrong. I didn't mean Topping in particular, but in general. Makes sense, now that it's been explained. I will have to see if I can notice it once my XLR headphone cable arrives.

No no. No problem.

 

[survivingscout]

I would make the assumption based off of what I have heard and read about the A90 that this extra noise on the XLR headphone out would likely be inaudible?

Also, I had not idea that planars can benefit from the extra voltage of XLR? That could be interesting for my HE4xx that I'm using until I can audition some ZMF headphones (when Illinois' lockdown eases up). I'll have to order an XLR cable for my HE4xx to try this out!

 

[JohnYang1997]

I would make the assumption based off of what I have heard and read about the A90 that this extra noise on the XLR headphone out would likely be inaudible?

Also, I had not idea that planars can benefit from the extra voltage of XLR? That could be interesting for my HE4xx that I'm using until I can audition some ZMF headphones (when Illinois' lockdown eases up). I'll have to order an XLR cable for my HE4xx to try this out!

Specifically SUSVARA, HE6, HE6s and akg k1000, HEDDPhone the real power hungry ones. But I still think single ended output has enough power.

 

[frogmeat69]

Specifically SUSVARA, HE6, HE6s and akg k1000, HEDDPhone the real power hungry ones. But I still think single ended output has enough power.

The A90 definitely has the power for my HE6se cans through the XLR output, makes those headphones sound full, nothing lacking.
People who say you need speaker taps and a big amp must be frigging deaf already, lol.

 

[EdW]

It's probably going to be the Soncoz LA-QXD1 or the SMSL SU-8 (210€ on amazon), unless I find an offer on the D70/90.

Also would there be soundwise any differences by following cable linkings?
1) USB Type B (DAC) -> USB-C (Macbook pro 2020)
2) USB Type B (DAC) -> Usb Hub Adapter of Macbook Pro
3) Coax IN (DAC) -> SPDIF OUT (Focusrite 8i6) // Would use it 80% like this

The Soncoz measures significantly better with no IMD hump according to Amir, although it has no remote or internal power supply. Probably a better match to A90 quality. Look at the review pages for the respective DACs to get the review itself and other members’ views and experiences.

1. dac fed from MacBook - fairly similar to Amir’s setup - except he uses a PC. So should be good
2. dac fed via hub - Should be good too. The hub might catch some HF noise? Try it.
3. From focusrite - sorry, no idea how the focusrite performs but both DACs just fine on coax I/P according to Amir

 

[ReaderZ]

That's not really fair to say that. However it's understandable that regular people don't understand.

Firstly, you can go to Massdrop 789's page, check the specifications of that. You will see that balanced output is twice as noisy. So by showing this, it's not just A90 that has this property.

Now, if you have access to Douglas Self's small signal book(or doesn't matter if you don't), it's said that balance connection is inherently more noisy than single-ended. While this is not intuitive, it's actually true. If you have balanced to single ended or single ended to balanced conversion, you get even more noise(relatively). Balanced connection however have better rejection to interference.

At this moment, we established that this is common and not a strange phenomenon.

Then, in comparison, A90's balanced output, even though is relatively more noisy than single-ended output, has much less noise of single ended output on many amplifiers even compared with 789. 0.6uV vs 1.2uV. Single ended output of A90 is just lower at 0.2uV. Probably the lowest on the market, at least to my knowledge.

Lastly, does it matter. Maybe yes maybe no. Most of the headphones aren't noisy with over 4uV noise. Most sensitive IEMs can produce audible noise with 0.8uV noise. So it really depends. For the user, just try it. Pretty simple.

HMM，now, on DX7 Pro's review page, the balanced has less noise than SE out. What's different about it?

 

[JohnYang1997]

HMM，now, on DX7 Pro's review page, the balanced has less noise than SE out. What's different about it?View attachment 73075

The circuit is not optimized. Also it involves DAC, where single ended output usually has differential amplifier that gets noisy. You can think of it as there's no real single ended in the beginning. And the single ended is derived from the balanced signal. Hence more noise.
It may not be always the case.

 

[ReaderZ]

The circuit is not optimized. Also it involves DAC, where single ended output usually has differential amplifier that gets noisy. You can think of it as there's no real single ended in the beginning. And the single ended is derived from the balanced signal. Hence more noise.
It may not be always the case.

I see, that make perfect sense.

 

[A.Cristea]

The Soncoz measures significantly better with no IMD hump according to Amir, although it has no remote or internal power supply. Probably a better match to A90 quality. Look at the review pages for the respective DACs to get the review itself and other members’ views and experiences.

1. dac fed from MacBook - fairly similar to Amir’s setup - except he uses a PC. So should be good
2. dac fed via hub - Should be good too. The hub might catch some HF noise? Try it.
3. From focusrite - sorry, no idea how the focusrite performs but both DACs just fine on coax I/P according to Amir

About point 3 (focusrite 6i8 3rd gen), i think I wouldn't pick the DAC conversion from the focusrite. The soundcard would (apparently?) just work as a bridge.

 

[Harmonie]

That's not really fair to say that. However it's understandable that regular people don't understand.

Firstly, you can go to Massdrop 789's page, check the specifications of that. You will see that balanced output is twice as noisy. So by showing this, it's not just A90 that has this property.

Now, if you have access to Douglas Self's small signal book(or doesn't matter if you don't), it's said that balance connection is inherently more noisy than single-ended. While this is not intuitive, it's actually true. If you have balanced to single ended or single ended to balanced conversion, you get even more noise(relatively). Balanced connection however have better rejection to interference.

At this moment, we established that this is common and not a strange phenomenon.

Then, in comparison, A90's balanced output, even though is relatively more noisy than single-ended output, has much less noise of single ended output on many amplifiers even compared with 789. 0.6uV vs 1.2uV. Single ended output of A90 is just lower at 0.2uV. Probably the lowest on the market, at least to my knowledge.

Lastly, does it matter. Maybe yes maybe no. Most of the headphones aren't noisy with over 4uV noise. Most sensitive IEMs can produce audible noise with 0.8uV noise. So it really depends. For the user, just try it. Pretty simple.

Appreciate your point.
In case a setup has no hum or noise and that you do not need the extra double output voltage:
I wonder if there is any benefit to use balanced cords ?
A better solution could be relative short (6 foot) RCA cables not crossing/overlapping over others ?

 

[JohnYang1997]

Appreciate your point.
In case a setup has no hum or noise and that you do not need the extra double output voltage:
I wonder if there is any benefit to use balanced cords ?
A better solution could be relative short (6 foot) RCA cables not crossing/overlapping over others ?

For headphone cable/jack/plug,
Channel separation with low impedance load. Other than this, there's none.

For interconnects, if there's no interference then there's absolutely no benefits.

 

[Harmonie]

For headphone cable/jack/plug,
Channel separation with low impedance load. Other than this, there's none.

For interconnects, if there's no interference then there's absolutely no benefits.

Merci beaucoup,
I'm sure that your reply may help many others.

 

[Tup3x]

Gotta admit... I find A90 quite appealing. Not needing another power brick is definitely a plus and part of me just wants an excuse to be able to use balanced cable (from HD 660 S). Maybe I'll just end up wasting my tax returns for this and live happily ever after. It would be end game for me when it comes to headphone amps.

 

[frogmeat69]

Gotta admit... I find A90 quite appealing. Not needing another power brick is definitely a plus and part of me just wants an excuse to be able to use balanced cable (from HD 660 S). Maybe I'll just end up wasting my tax returns for this and live happily ever after. It would be end game for me when it comes to headphone amps.

Yeah, wish more stuff was like this, would make the bird's nest behind my desk a bit more manageable.

 

[Veri]

Gotta admit... I find A90 quite appealing. Not needing another power brick is definitely a plus and part of me just wants an excuse to be able to use balanced cable (from HD 660 S). Maybe I'll just end up wasting my tax returns for this and live happily ever after. It would be end game for me when it comes to headphone amps.

For me it does all you mention and more. Highly recommended

 

[GeorgeWalk]

Gotta admit... I find A90 quite appealing. Not needing another power brick is definitely a plus and part of me just wants an excuse to be able to use balanced cable (from HD 660 S). Maybe I'll just end up wasting my tax returns for this and live happily ever after. It would be end game for me when it comes to headphone amps.

I have the A90 with the HD 660s it is a great pairing. The A90 has enough power to drive the HD660 S to ear splitting levels without distrotion. I have used both balanced and unbalanced and I can't hear a difference. Now, I mostly use the unbalanced because the cord is longer and less stiff. I also have the D90. For me, I am at the endgame of DAC/Amp/headphone gear.

 

[nyj585]

How are the single ended outputs on these? Is the sound quality/signal different between what is being fed to the XLR or 4.4 output versus the 3.5mm output? I have been told the single ended output on these balanced amps usually fall short of the XLR output.

These balanced headphone amps always measure amazingly, but I don't have any headphones/cables that are balanced aside from a 4.4 balanced cable for one of my IEMs. If I understand correctly, all a headphone needs to be balanced is separate connectors to left and right and a cable. So headphones like the Argon Mk. III and the DT 1990 Pros have only one connector so I know they'll need a internal wiring modification to run balanced correct? But something like the Sennheiser 6XX just needs a balanced cable to run. Am I understanding this right?

 

[GeorgeWalk]

I can't hear any difference between XLR and unbalanced.

The Sennheiser 660S has detachable cables. So you can switch between balanced and unbalanced just by changing the cable. The headphone is wired internally to handle this switch.

 

[nyj585]

I can't hear any difference between XLR and unbalanced.

The Sennheiser 660S has detachable cables. So you can switch between balanced and unbalanced just by changing the cable. The headphone is wired internally to handle this switch.

Yeah I figured. I have just heard others saying that the single-ended output is an afterthought on these balanced amp designs and usually dip in quality compared to the XLR out. I suppose it does sound louder on XLR and maybe this is being perceived as an increase in fidelity, hence the single ended is worse belief?

So do headphones have to be internally wired for balanced even with separate left and rights? I always thought that cables were balanced or unbalanced rather than headphones. And that the only internal wiring changes that are required for headphones are if they don't have separate right and left plug-ins on the cable meaning the cable only connects to one side of the headphone. But anything that has separate left and rights, meaning the cable splits into each side of the headphone just needs a cable wired for balanced with an balanced terminal like XLR, 4.4 etc. Am I incorrect on this? Sorry, I am new to balanced as I only worked with RCA and single-ended outputs so just trying to get an understanding if I decide to make the leap to a balanced headphone amp.