Topping A90 Headphone Amplifier Review

[Audimon]

So you can choose L30 and a50s.

I couldn't find the exact specs but I doubt they mirror A90 because feature wise it is perfect for me.
I am planning to use all of A90 inputs and outputs.
RME will feed tube pre to A90 via RCA, then A90 RCA out will feed bluetooth transmitter for when I need to move around sending to FiiO BTR-5.
Balanced RME out will feed balanced A90 in and then go balanced out of A90 to active monitors.
and for the front I also have plans for XLR and 4.4
If not for all the above communication and XLR front socket could have as well stayed with the RME internal amp, it's quite good.

 

[bequietjk]

Does anyone know the official weight of the A90? I suspect it to be a good chunk considering the internal power supply.

 

[JohnYang1997]

Does anyone know the official weight of the A90? I suspect it to be a good chunk considering the internal power supply.

1.25Kg

 

[Kesi]

what is your headphone ?

I’m using my 6 year old LCD2 Fazor and HD800s (currently with my brother) so I’m stuck with the LCD2.

 

[JohnYang1997]

I couldn't find the exact specs but I doubt they mirror A90 because feature wise it is perfect for me.
I am planning to use all of A90 inputs and outputs.
RME will feed tube pre to A90 via RCA, then A90 RCA out will feed bluetooth transmitter for when I need to move around sending to FiiO BTR-5.
Balanced RME out will feed balanced A90 in and then go balanced out of A90 to active monitors.
and for the front I also have plans for XLR and 4.4
If not for all the above communication and XLR front socket could have as well stayed with the RME internal amp, it's quite good.

L30 has a bit better single end than A90's. A50s has bal output that's more powerful than L30. They are all very good. The actual benefit of A90 is bal input and internal power supply. And surely A90 is more powerful. If you really like A90, just use it with XLR inputs. It's the easy way out.

 

[w1000i]

I’m using my 6 year old LCD2 Fazor and HD800s (currently with my brother) so I’m stuck with the LCD2.

I believe if you have HP with dynamic driver with good sensitivity will be better upgrade than going A90 for LCD2

 

[Audimon]

L30 has a bit better single end than A90's. A50s has bal output that's more powerful than L30. They are all very good. The actual benefit of A90 is bal input and internal power supply. And surely A90 is more powerful. If you really like A90, just use it with XLR inputs. It's the easy way out.

Guess I didn't explain well. I need ALL inputs and outputs of A90, balanced AND unbalanced. So anything with less ins/outs than A90 has doesn't work for me.
Also I am still waiting for my A90 from Shenzhen audio and it's been a month now. So I doubt I will want to go through sending it back and waiting for something else

 

[Kesi]

I believe if you have HP with dynamic driver with good sensitivity will be better upgrade than going A90 for LCD2

Element X produces enough bass, rumble and slam when I plug a low impedance HP. Sadly it was a loan from a friend. I might purchase the A90, i can sell it anytime If things got worse Thank you for taking time to reply. Your location (Jubail SA) from your profile reminds me moments etched on my head., watching patriot intercepts scud on Saudi Kuwait border during the gulf war.

 

[hmscott]

Since quite a few people complaining about noise on RCA, I would like to clarify here.

I have D90MQA and A90 paired with RCA (1 meter Van den hul the Source) , I did not hear any noise from my HD650 and HE4XX with low and medium gain tested. No test on high gain though as not required as of now.

Electrical system here is single phase (two-wire L & N and earth), power supply to D90 MQA/A90 is from wall wart with proper earthing

Hey guys!

I am having a noise problem with my Topping A90 at medium and high gain w/ my DT 1990s. There is a very noticeable buzz even when the gain nob is at the halfway point on medium gain. I am using RCA inputs from my motherboard dac (SABRE 9118 DAC ) (don't have an external DAC yet, need to decide on which on to get) and the 6.5mm headphone out.

The thing is I don't get nearly any noise when I use my THX 887 with the same outputs/inputs. Would this huge difference be caused by the internal computer noise and the A90 being much more powerful? It seems weird that there would be huge difference between the A90 and my THX 887. If I can't figure this out I am going to have to return the A90 unfortunately as the noise is too problematic.

Do you guys have any thoughts?

For me the noise doesn't present itself until the A90 is at M Gain 50% volume setting and higher, or H Gain. At L Gain and M Gain below 50% the noise is not noticeable. The D90 MQA was in DAC mode for that RCA configuration. Now I have XLR between the D90 MQA and A90 and there is no noise.

I am holding off on buying RCA connected powered speakers as those will have their own AC power connection with an "earth" ground and possibly will have the same noise problem connected to the A90 via RCA. I am looking for powered speakers with XLR inputs.

As for the RCA being sensitive to ground loop noises with 3-prong devices, I have had the same issue with all the headphone amps that do not use an external 2-prong power adapter.

If this is the only problem with the A90’s RCA inputs, it is a non-issue as it is endemic to any fully grounded amp (The Asgard, Burson Soloist etc.).

There are 2 ways to work around this problem without affecting the fidelity of the signal: get the EB Tech Hum X for $79 or get an USB isolator.

We shouldn't need to buy a AC isolator for $79+tax, and a power disconnect USB dongle for $58+tax, or make custom hacks to solve a problem that's under the control of Topping when designing the D90 / A90 to operate together. Both external solutions could be internal and integrated between Toppings own paired products.

There are enough of the noise issues reported with RCA connection's between the A90 and D90 that it is a significant percentage of those reporting their experience with the A90 and D90. At least the noise problem between their own pairing of products should be under Toppings complete control.

Even if you don't experience these issues in your current set up; setup's change over time and it may come a time when you wished there wasn't such a problem using RCA connections between the A90 and D90 (MQA). Once you have the problem you have spend time and money to resolve it.

Perhaps there is a solution to be made available by Topping - in control of their design of both the A90 / D90 MQA that allows this earthing problem to be resolved in future designs for all users to prevent these issues.

If nothing else a satisfactory outcome long term would be to plan and design a solution, whether it's built in to the design of the product(s) or provided as dongles with their product(s) to save their customers from known potential issues of interaction between Toppings paired products.

Besides these noise problems I discovered a oscillation Tone between the D90 MQA and A90 with the USB cable disconnected with XLR+RCA connections between the A90 / D90MQA - set in H Gain Zero volume there's a tone in the headphones output, some kind of interaction between the XLR and RCA paths, at least between my units. IDK, no one else has reported it - perhaps try it if you have the cables and see if you can replicate it.

 

[Audimon]

Making an inbuilt power supply because people don't like external power supply and then make dongles, perform voodoo dances, etc to get rid of the noise?
Just make an external power supply!

It's not like it's a 300 watt speaker amp I don't get it

 

[JohnYang1997]

Making an inbuilt power supply because people don't like external power supply and then make dongles, perform voodoo dances, etc to get rid of the noise?
Just make an external power supply!

It's not like it's a 300 watt speaker amp I don't get it

It's ground related. So it's system dependent. It's not like it's not usable in most cases just doesn't perform as well as on paper. Plus balanced connection works perfectly. Also no one is saying there won't be other products with external power supply. There will be and there will be several ones.

 

[Audimon]

It's ground related. So it's system dependent. It's not like it's not usable in most cases just doesn't perform as well as on paper. Plus balanced connection works perfectly. Also no one is saying there won't be other products with external power supply. There will be and there will be several ones.

That's understood but if it is possible to avoid even a possibility of the problem altogether, why not?

 

[JohnYang1997]

That's understood but if it is possible to avoid even a possibility of the problem altogether, why not?

I get that internal power supply is not important for you. But many people will think it's ridiculous to have a 499 dollar product with external power supply. Simple as that.
Can you imagine having D90 which has internal transformer then make A90 with external power supply that's supposed to pair with it.

 

[JohnYang1997]

Another thing is the way of thinking. Why you would expect "my" product to be immune to any potential systematic issue where it's allowed to have the same potential in other parts of the system. Why not use a DAC without earth like qutest or adi2dac, why not use toslink as well?

 

[maverickronin]

I think this may be the stupidest attempt at creating a controversy I've seen on ASR...

 

[Audimon]

I am not trying to be difficult. Sorry if it seems to be the case. I am just trying to clarify things for myself.
I thought that to most people who are busy with those boxes the most important thing was the sound - it's purity mainly but also quality and quantity.
It seems to me that these devices are all racing against each other to provide an edge in functionality, build quality, comfort and ease of use. But it is all supposed to be an addition to the original goal - purity of sound.
However if the original goal is compromised achieving other goals seems to miss the point.
In reply to your above message I did mention earlier that I AM using adi2dac actually.
Anyway it seems that it is a difference in a way of thinking issue and there is no single answer, so I rather avoid any further heating of the discussion
Thank you for your patience and honest replies JohnYang1997

 

[Audimon]

I think this may be the stupidest attempt at creating a controversy I've seen on ASR...

Sometimes things perceived not the way the were intended.
Think about that.

 

[JohnYang1997]

I am not trying to be difficult. Sorry if it seems to be the case. I am just trying to clarify things for myself.
I thought that to most people who are busy with those boxes the most important thing was the sound - it's purity mainly but also quality and quantity.
It seems to me that these devices are all racing against each other to provide an edge in functionality, build quality, comfort and ease of use. But it is all supposed to be an addition to the original goal - purity of sound.
However if the original goal is compromised achieving other goals seems to miss the point.
In reply to your above message I did mention earlier that I AM using adi2dac actually.
Anyway it seems that it is a difference in a way of thinking issue and there is no single answer, so I rather avoid any further heating of the discussion
Thank you for your patience and honest replies JohnYang1997

At the end of the day, it's actually about making a product than else. Just being able to reproduce pure sound is not the same as making a good product that actually makes sense in a lot of places. And one single product can't satisfy all the people.
I like discussions. No hard feelings.

 

[hmscott]

I get that internal power supply is not important for you. But many people will think it's ridiculous to have a 499 dollar product with external power supply. Simple as that.
Can you imagine having D90 which has internal transformer then make A90 with external power supply that's supposed to pair with it.

Actually isolating the power supply external to the signal path - reducing the influence - even separating into separate closed enclosures is common. Battery power for desktop audiophile equipment is also common.

Figuring out how to connect the grounds, or isolate the grounds between equipment is part of the design for getting paired components to work together without induced interference. Avoiding

Avoiding interference by pulling out the power generation components and using a common ground between components is basic design principle. If you ignore that then this is what we get. Random induced interference experienced by some and not by others, with the burden of figuring out a solution now put onto the customers instead of easily resolved in the design stages and tested to be effective before production.

You'll figure it out

 

[hmscott]

Another thing is the way of thinking. Why you would expect "my" product to be immune to any potential systematic issue where it's allowed to have the same potential in other parts of the system. Why not use a DAC without earth like qutest or adi2dac, why not use toslink as well?

Why provide USB connectivity if you can't reject the noise through isolation? Why allow the source USB power to be pulled internal to the D90 when it doesn't use the power? Why provide RCA connections when you can't stop the ground loop interference between your own equipment?

These are valid questions as well, and I hope you consider them in future designs.

At the end of the day, it's actually about making a product than else. Just being able to reproduce pure sound is not the same as making a good product that actually makes sense in a lot of places. And one single product can't satisfy all the people.
I like discussions. No hard feelings.

It's all one of the same. If you can't enjoy the excellent sound reproduction from your components due to failure to account for noise rejection from the outside, and design your components to work together, at the very least, without affecting each others ability to reject noise induced, then the original goal of providing sound reproduction isn't attainable, at least for all of your customers.

It's not an unusual configuration. D90 MQA + A90 + USB source from PC - is it? Many will run into the same issues, if not at first then later.

No hard feelings, but there is disappointment that has to be acknowledged. You'll lose customers and next time they will be wary to purchase without waiting for initial rollout to happen and see how the products work before buying. Losing that "unthinking support" that drives high product sell through initially can be more than disappointing.

Like I've said, I think you'll work it out.