Topping A900 released: insane beast

[dasherzx]

Given that the A50s is already transparent, why do we need more flagships? It's not like they're going to sound any different.

the output power on these is insane, the hifimans like the susvara and he6se should benefit from this over the a50s. but other than that they really are diminishing returns. topping should just enter the atmos HT pre-amp market

 

[Roland68]

topping should just enter the atmos HT pre-amp market

Only if you want to ruin Topping as a company.

Topping hasn't been able to completely fix the problems with the DX5 II, including PEQ and a few other minor issues, for months; an atmos HT pre-amp would be significantly more complex.

 

[dasherzx]

Only if you want to ruin Topping as a company.

Topping hasn't been able to completely fix the problems with the DX5 II, including PEQ and a few other minor issues, for months; an atmos HT pre-amp would be significantly more complex.

i only buy used toppings, because ill know it has worked and will probably work for awhile longer. i like to believe its a big brain move on my end. its meaningless now anyway, since minidsp has released the be all and end all of ht preamp (if it works as well as their existing product line)

 

[BigTy120]

My post wasn’t exactly accurate. I have a variety of headphones (mostly planars). Not all were as sensitive but suffered from the same issues of the audio cutting off and this was definitely common as I searched other forums. It’s a Topping QC problem. For me, purchasing a Topping product is like a dose of anxiety honestly. But the A900 seems so impressive.

I too have had the same issues with Topping amps going into safe mode with the hp dc abnormal message. alot of Topping guys dont like it when you bring up this very common error with their amps.

 

[Manu91440]

The reason I'm so keen on headphone amplifiers like this is they also make good pre-amps. I think preamps are rather under-rated, and there aren't that many good ones. You can pay a lot of money for a preamp, if you want to.

They're particularly good for Topping, Benchmark, Hypex and Purifi amplifiers that have (optional) low input sensitivity and sometimes low input impedance ( View attachment 4778821kΩ). They need a preamp or buffer stage with high output voltage, and preferably low output impedance and high current delivery. And adequate audio envelope and fidelity not to compromise the performance of the amp.

It's a tall order, but I suspect many buffer stages (even the expensive ones) drag the amplifier down slightly.
Amir has tested several amps at different sensitivity / gain settings, and they all perform best at low gain.

To get a handle on the requirements and achievements of actual buffers, I used data from Purifi tests to generate a system model.
The model has three stages - the source, the buffer, and the power amp.
I treated each stage as an amplifier, with an input voltage, gain, output voltage, and noise and distortion that it adds to the source and feeds to the power amp.

View attachment 477895

In the spreadsheets, the shaded cells are the input parameters, the orange ones are the variables, and the green one is the output.
To model the tests I supposed the source was an APx555 analyser with an imaginary clean input signal of 1V, plus 12.5dB gain and 1µV noise (DNR 132dB).
The power amp was a 1ET400 with no buffer, 12.8dB gain and 6.6µV noise (DNR 136dB).
By modelling the buffer with 7dB gain and 5.3µV noise, I got the end result to match Amir's amplifier tests at high gain.
Although every stage contributed to the end result, the buffer had a DNR of 125dB, and was clearly the bottleneck in the system.
Alternatively, you can see in the buffer the internal noise dominates the signal noise, yet in the amp the signal noise dominates it's internal noise.
The end result is a system DNR of 124dB (still really good) but limited by the buffer.

View attachment 477896

I then modelled the preamp as a Topping A70Pro with 7dB gain and (pessimistically) 1µV noise (DNR 139dB)
This time, the overall system DNR is increased from 124 to 130dB.
The signal noise dominates the internal noise in the preamp, and the amplifier output noise is halved compared with the buffer.
Every stage contributes to the end result, but now the system performance is predominantly constrained by the source.
I also performed the same analysis with THD+N, but the conclusions are simpler and clearer by just considering noise.

The expensive Sparkos, Sonic Imagery or Weiss discrete op-amps measure no better than good integrated solutions, and cost hundreds more.
That money could be spent on a good headphone / preamp like the L30, L50 or A70, and get better performance.
I recently did a money-no-object model with a Topping D900 / A900 combo and 1ET9040 amp, and got an even better result:

View attachment 477897

Hello,
Do you think it would be benificial to connect the D900 13v preamp outputs directly to the 1et400 bypassing the buffer? From what I read the D900 are very low impedance.
Thank you, Emmanuel

 

[welwynnick]

Hello,
Do you think it would be benificial to connect the D900 13v preamp outputs directly to the 1et400 bypassing the buffer? From what I read the D900 are very low impedance.
Thank you, Emmanuel

Are you in a position to try it for yourself? Do you already have a D900 and a Purifi amplifier?
The D900 has enough output voltage to drive the 1ET400 directly.
The input impedance of the unbuffered 1ET400 is 4400 ohms, which is unusually low. The output impedance of the D900 is 100 ohms, which is normal rather than unusually low.
The impedance ratio is acceptable rather than comfortable.
If you used a the output of a good headphone amp, that would have less than one ohm output impedance, and that would be very comfortable.

 

[Manu91440]

Are you in a position to try it for yourself? Do you already have a D900 and a Purifi amplifier?
The D900 has enough output voltage to drive the 1ET400 directly.
The input impedance of the unbuffered 1ET400 is 4400 ohms, which is unusually low. The output impedance of the D900 is 100 ohms, which is normal rather than unusually low.
The impedance ratio is acceptable rather than comfortable.
If you used a the output of a good headphone amp, that would have less than one ohm output impedance, and that would be very comfortable.

Thank you for your answer, yes I have purifi's amps with neurochrome universal buffer, and no D900 yet. I'm hesitating between gustard x30, D900 and eversolo Z10 to replace my rme adi 2. Not sure I will really feel a benefit in doing so

 

[BeeKay]

Alternatively there is the A70 Pro with
54 Vpp ~ 19,1 Vrms

 

[welwynnick]

Alternatively there is the A70 Pro with
54 Vpp ~ 19,1 Vrms

I was thinking along similar lines. A D70 Pro Octo or Pro Sabre paired with an A70 Pro would be a formidable combo (and still less than a D900).
The A70 still has the relay switched resistor volume control, and very high output level, and very low output impedance (0.1 ohm) if you use the headphone output.

Thank you for your answer, yes I have purifi's amps with neurochrome universal buffer, and no D900 yet. I'm hesitating between gustard x30, D900 and eversolo Z10 to replace my rme adi 2. Not sure I will really feel a benefit in doing so

Having you tried driving the Purifi directly with the RME and by-passing the buffer? I think that might work well. I would try that before making a decision on a Topping.

 

[Manu91440]

Thank you for your answer.
The rme is only 5v out of xlr, purifi need 11 by memory. So I didn't try.
The more I'm reading about dacs preamp etc the less I want to buy something there is always something not good or missing or a bad review that you end up completely lost

 

[welwynnick]

Thank you for your answer.
The rme is only 5v out of xlr, purifi need 11 by memory. So I didn't try.
The more I'm reading about dacs preamp etc the less I want to buy something there is always something not good or missing or a bad review that you end up completely lost

The better DACs and preamps by RME, Eversolo, SMSL, Gustard and Topping are all pretty much beyond technical reproach these days.
What are your concerns?
There's the odd chink in the armour such as the Topping L30 reliability, E30 II jitter on spdif, or the Pre90 low input impedance, but those chinks are few and far between.
There might not be much to gain by upgrading the RME, but I think using a good, cheap, headphone amp as a preamp to "replace" an input buffer would be worthwhile.
That's why I bought my L70, and I'd recommend it to everyone. You could spend more on an A70 or A900, but you won't get much more output or performance.

 

[boXem]

The rme is only 5v out of xlr

May I suggest to re-read the datasheet?

 

[Manu91440]

May I suggest to re-read the datasheet?

I will t confirm XLR V out, and impedance, as I think purifi amp have a quite "high" input impedance, not sure if it's a problem for rme to drive it directly (bypassing the buffer)
Thank you for the recommandation

 

[welwynnick]

I will t confirm XLR V out, and impedance, as I think purifi amp have a quite "high" input impedance, not sure if it's a problem for rme to drive it directly (bypassing the buffer)
Thank you for the recommandation

The Purifi modules themselves have a relatively low input impedance - hence the need for a buffer.
The input impedance of the buffer is high.

 

[Manu91440]

The better DACs and preamps by RME, Eversolo, SMSL, Gustard and Topping are all pretty much beyond technical reproach these days.
What are your concerns?
There's the odd chink in the armour such as the Topping L30 reliability, E30 II jitter on spdif, or the Pre90 low input impedance, but those chinks are few and far between.
There might not be much to gain by upgrading the RME, but I think using a good, cheap, headphone amp as a preamp to "replace" an input buffer would be worthwhile.
That's why I bought my L70, and I'd recommend it to everyone. You could spend more on an A70 or A900, but you won't get much more output or performance.

Yep, I feel like dac's differences are very minor nowadays due to general high level of them.
My wish would be to "analog" /warm up a bit my general sound, which can be a bit edgy on some records due to my high revealing/neutral chain (rme adi 2/purifi amps with neurochrome universal buffer/sasandu tx speakers)
I really love this combo and it's general balance/dynamic, just to warm it up a bit if it's possible.
I was also reading about the aiyima t20 preamp to give it a try.
I'm going to check your L70 option now
Thank you

 

[welwynnick]

I don't think the Topping D900 would be the solution for your system.

 

[Manu91440]

The Purifi modules themselves have a relatively low input impedance - hence the need for a buffer.
The input impedance of the buffer is high.

OK, so to you there is no problem in driving the purifi balance input directly from rme? I think removing parts from the signal pass could be only benifitial. Maybe I'm wrong

 

[welwynnick]

I believe the RME has a max output level of +19dBu at high gain, which is about 7V. Therefore it's not enough to drive a Purifi amp to full power. However it might be close enough to give you a good idea of what it might sound like. The output impedance is 75 ohm, so pretty low, and it's probably fine for by-passing the Purifi buffer. I found a test where an RME was run into a low impedance load and it performed well with very little loss of gain or increase in distortion. I'll see if I can find it.

EDIT: Here's the test of an RME UFX that I was thinking of. It's very comprehensive. While the RME isn't quite state-of-the-art, it's not a one trick pony with just a high SNR to it's name. It's good by every single objective measure.

RME UFX III Audio Interface review

This is a review and detailed measurements of the RME UFX III professionnal Interface (ADC, DAC, Headphones Amp). The UFX III is quite recent, as it was launched around march 2023. Normal price is around 2700€. I purchased mine new. Presentation The UFX III is the current top of the RME...

www.audiosciencereview.com

There's another one here. Again it's very good in every single respect.

SoundStageNetwork.com | SoundStage.com - RME ADI-2 DAC FS Digital-to-Analog Converter Measurements

www.soundstagenetwork.com

The chart above shows THD ratios at the balanced line-level output into 200k ohms (blue/red) and 600 ohms (purple/green) as a function of frequency for a 24/96 dithered 1kHz signal at the coaxial input. The 200k- and 600-ohm data are nearly identical throughout the audioband, which is in indication that ADI-2 DAC FS’s outputs are robust and can handle loads below 1k ohms with no difficultly.

 

[Manu91440]

I believe the RME has a max output level of +19dBu at high gain, which is about 7V. Therefore it's not enough to drive a Purifi amp to full power. However it might be close enough to give you a good idea of what it might sound like. The output impedance is 75 ohm, so pretty low, and it's probably fine for by-passing the Purifi buffer. I found a test where an RME was run into a low impedance load and it performed well with very little loss of gain or increase in distortion. I'll see if I can find it.

EDIT: Here's the test of an RME UFX that I was thinking of. It's very comprehensive. While the RME isn't quite state-of-the-art, it's not a one trick pony with just a high SNR to it's name. It's good by every single objective measure.

RME UFX III Audio Interface review

This is a review and detailed measurements of the RME UFX III professionnal Interface (ADC, DAC, Headphones Amp). The UFX III is quite recent, as it was launched around march 2023. Normal price is around 2700€. I purchased mine new. Presentation The UFX III is the current top of the RME...

www.audiosciencereview.com

There's another one here. Again it's very good in every single respect.

SoundStageNetwork.com | SoundStage.com - RME ADI-2 DAC FS Digital-to-Analog Converter Measurements

www.soundstagenetwork.com

Thank you a lot, very interesting even if above my technical skills that's also why I was heading toward the D900 which looks to have an even beefier preamp, 1 bit maybe smoother than delta sigma, Bluetooth and PEQ for minor adjustments if needed

 

[Manu91440]

I believe the RME has a max output level of +19dBu at high gain, which is about 7V. Therefore it's not enough to drive a Purifi amp to full power. However it might be close enough to give you a good idea of what it might sound like. The output impedance is 75 ohm, so pretty low, and it's probably fine for by-passing the Purifi buffer. I found a test where an RME was run into a low impedance load and it performed well with very little loss of gain or increase in distortion. I'll see if I can find it.

EDIT: Here's the test of an RME UFX that I was thinking of. It's very comprehensive. While the RME isn't quite state-of-the-art, it's not a one trick pony with just a high SNR to it's name. It's good by every single objective measure.

RME UFX III Audio Interface review

This is a review and detailed measurements of the RME UFX III professionnal Interface (ADC, DAC, Headphones Amp). The UFX III is quite recent, as it was launched around march 2023. Normal price is around 2700€. I purchased mine new. Presentation The UFX III is the current top of the RME...

www.audiosciencereview.com

There's another one here. Again it's very good in every single respect.

SoundStageNetwork.com | SoundStage.com - RME ADI-2 DAC FS Digital-to-Analog Converter Measurements

www.soundstagenetwork.com

I always have the doubt if it's better to have the preamp at high level and buffer low gain setting or the opposite, Regarding distortion dynamic timbres etc