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Topping Pre90 Review (preamplifier)

Pdxwayne

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This is a review and detailed measurements of the Topping Pre90 balanced and unbalanced preamplifier. It was kindly sent to me by the company. The base preamplifier with ability to switch between RCA and XLR inputs costs US $599. There is an extension that gives you four (4) more inputs (three balanced and one unbalanced) for another $250.

Splitting the functionality into two boxes is rather unique:

View attachment 98412

Unfortunately there is no immediately switch to select an input. You have to cycle through them using the "SEL" button on the left.

Remote control is provided for volume which in turn mandated relay based stepped attenuator which is quite a "high-end" feature. For any kind of home system use remote is mandatory in my book so it is great to see it implemented here. There are other cool features like setting a pre-input gain or maximum safe playback level.

The back panel shows the unusual configuration with the umbilical cord connecting the two:

View attachment 98413

As you see mains power supply is built-into it as it should in this price category.

Overall fit and finish is very good.

For my testing I exclusively focused on XLR input and output.

Topping Pre90 Measurements
As usual I setup preamplifiers for "unity gain" meaning what voltage I put in, is what comes out. On Pre90 that meant setting the volume to -6 dB instead of zero. That gives us this eye popping output:

View attachment 98414

Distortion is whopping -25 dB lower than best case threshold of hearing. Combined noise+distortion as represented by SINAD is 5 dB better than said threshold. And this includes the noise from my analyzer. Likely the actual performance is fair bit better.

Suspecting some of the good noise figure comes at the expense of lower than normal input impedance, I jacked up the default 40 ohm output impedance of my Audio Precision analyzer to 200 ohm. The result was that the output from the Pre90 dropped down to 3.6 volts (instead of 4). One click on the volume control compensated for that nicely and give me the same good performance just as well:

View attachment 98416

So there is really no penalty to the lower input impedance.

I wanted to test the effect of the external box so I selected one of its inputs and ran the dashboard again (with 40 ohm impedance);

View attachment 98424

As you see the external input works just as excellently as the internal input.

EDIT: here is the RCA performance:
View attachment 98630

Signal to noise ratio (combined with my analyzer input) is 21 bits and rises to almost 22 bits with full volume:
View attachment 98429

Note that Topping advertises much higher numbers. They do that by using a noise amplifier, measuring the results with AP, and then dividing the output by the gain of the noise amplifier. By doing so the remove the effect of Audio Precision analyzer's self noise and get much higher SNR. That is customary in chip industry. For us to keep things consistent we will continue to test as we have as any performance above what I am showing is academic anyway.

Note that the Pre90 can go up to +10 dB gain. Doing so though has a penalty in overall noise. To show the effect of output level/gain, here is a sweep:

View attachment 98435

As you see you can get to 8 volts while maintaining the full performance of the preamp. There is more gain left if you want to drive an amplifier like Benchmark AHB2 in low gain or Purifi without its input buffer.

Frequency response is almost flat to 80 kHz:
View attachment 98436

There is a bit more droop in my measurements vs Topping. Not sure why but it is immaterial.

Crosstalk was more than good enough for what we need but shy of the best that can be done:

View attachment 98438

Intermodulation distortion test is as good as the best I have tested, the Benchmark HPA4:
View attachment 98439

Same is the case for SINAD vs frequency:

View attachment 98440

Conclusions
Seems like the revolution we have had in high performance headphone amplifiers has bled into preamplifiers. I love it because I have a Reel Reel tape deck that I like to use occasionally in my system along with my usual DAC. Sadly hardly any premplifier could keep up with said DAC so I was degrading the performance of it to have the ability to play another analog source. With the Pre90, that compromise is no more. It is an instrument grade, more transparent than transparent, preamplifier. Other than Benchmark HPA4, I don't think it has an equal no matter how much money you spend. In that regard, it is quite a value as well although obviously not "cheap" as compared to desktop products.

It is my pleasure to strongly recommend the Topping Pre90. If you needed to have another source beside your DAC to play in your system, you now have a wonderful way to accomplish that with zero impact on performance.

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As always, questions, comments, recommendations, etc. are welcome.

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Amir, are you currently using one in your setup? Or are you using a different preamp?

I am curious if I could get noticeable improvement if using one between my Gustard x16 and my amp. Currently I am using x16 volume control at-15db to -20db for most songs.

Thanks!
 

Docmoggy

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I bought one over the Internet from a Chinese seller. How exciting! I could have bought the LA4. It's £2900 pounds here in the U.K. And the Pre90+Ext. was £409. That's £2500 pounds cheaper for a product that performs equally well. Now, I am a big fan of USA audio brands, but I just couldn't bring myself to buy the Benchmark even though I have the AHB2! My final decision was based on spending money where it was required in priority. The Topping will help the Mytek's feeble XLR output voltage drive the AHB2s. That's all I need. Benchmark should drop in a similar product imo. Here's another thing, I'm buying the Benchmark xlr cables and seeing if there is a difference between my incredibly stupidly priced chord version. Blind test here it comes! I have to get rid of my audiophile madness!
 

misterdog

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Ha, you are following in my footsteps. :)

All you need now is an SMSL M400 with 5.2V output to run your AHB2 in low gain mode.

Though I have just ordered a Gustard X16 to compare, as it has a much better multitone IMD and linearity, but 'only' 4V out.
Technically all the better measures of the X16 are below -115 dB so should make no audible difference, remains to be seen, or not as I will be wearing a blindfold :)
 
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Docmoggy

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Ha, you are following in my footsteps. :)

All you need now is an SMSL M400 with 5.2V output to run your AHB2 in low gain mode.

Though I have just ordered a Gustard X16 to compare, as it has a much better multitone IMD and linearity, but 'only' 4V out.
Technically all the better measures of the X16 are below -115 dB so should make no audible difference, remains to be seen, or not as I will be wearing a blindfold :)
It is a voyage of discovery! The Mytek BB is good enough I think and it is practical with the internet directly sourced. Great for Tidal. Wonder why Amir hasn't tested one yet? I know there are a lot of shenanigans going on between Hem and Mytek USA. Also with the BB you can drop in 12v DC.
 

ohnonate

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Any help would be great.
I have Blue sound node 2i (Using app for volume) connected to my Denafrips Ares II via Coax then into my Elac Navis ARB51 XLR. It seems i am not getting any sound improvements ? I am getting the same quality of sound when i just had them connected to the Blue sound node 2i.
How can this be right?
The more i look into this am i maybe missing something with impedance miss matching? and by connected a pre amp such as the topping Pre90 between the DAC and the active speakers i may unlock the full potential from the DAC? By boosting the signal from the DAC to the actives?

Could this be right? does anyone agree this maybe my issue?

So i have read the following - Ares 2 Should not be used with a pre amplifier or amplifiers with input impedance of less than 10,000 ohms.

I assuming the pre 90 should be fine as it it 1.44k ohm

Your help would be great
Thanks
 

Jimbob54

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Any help would be great.
I have Blue sound node 2i (Using app for volume) connected to my Denafrips Ares II via Coax then into my Elac Navis ARB51 XLR. It seems i am not getting any sound improvements ? I am getting the same quality of sound when i just had them connected to the Blue sound node 2i.
How can this be right?
The more i look into this am i maybe missing something with impedance miss matching? and by connected a pre amp such as the topping Pre90 between the DAC and the active speakers i may unlock the full potential from the DAC? By boosting the signal from the DAC to the actives?

Could this be right? does anyone agree this maybe my issue?

So i have read the following - Ares 2 Should not be used with a pre amplifier or amplifiers with input impedance of less than 10,000 ohms.

I assuming the pre 90 should be fine as it it 1.44k ohm

Your help would be great
Thanks

Why did you expect an improvement?
 

Rottmannash

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Any help would be great.
I have Blue sound node 2i (Using app for volume) connected to my Denafrips Ares II via Coax then into my Elac Navis ARB51 XLR. It seems i am not getting any sound improvements ? I am getting the same quality of sound when i just had them connected to the Blue sound node 2i.
How can this be right?
The more i look into this am i maybe missing something with impedance miss matching? and by connected a pre amp such as the topping Pre90 between the DAC and the active speakers i may unlock the full potential from the DAC? By boosting the signal from the DAC to the actives?

Could this be right? does anyone agree this maybe my issue?

So i have read the following - Ares 2 Should not be used with a pre amplifier or amplifiers with input impedance of less than 10,000 ohms.

I assuming the pre 90 should be fine as it it 1.44k ohm

Your help would be great
Thanks
Any difference will be subtle. Don't expect fireworks.
 

ohnonate

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Any difference will be subtle. Don't expect fireworks.
I think my expectation were high. I was thinking the different technology would have mad a larger difference. I will admit the bluesound node 2i for a streamer and DAC aint to bad at all for its quality and price. when the denafrips is nearly double the cost.
 

Veri

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So i have read the following - Ares 2 Should not be used with a pre amplifier or amplifiers with input impedance of less than 10,000 ohms.
I assuming the pre 90 should be fine as it it 1.44k ohm
Actually, "should not be used with less than 10kOhm", and pre90 is 1.44kOhm? That is not ideal then, you will notice a voltage drop. But besides that there should in theory not be any bad side effect on sound.
Input impedance of pre90 RCA is higher, you could try Ares 2 RCA into Pre90 and see if it's any "better". But like the others said, pre90 can yield a slight SNR benefit due to the superb pre-amp performance, but will that be audible? Maybe not...
 

pma

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That IMO too low impedance is used to get the best numbers (on paper) re the OPA1612 used (most probably in inverting mode with input series resistor that defines the input impedance). With special low-noise JFETs, there would be no need to keep such low impedance.

1617353073384.png
 
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Docmoggy

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Just reporting back on my views on the Pre 90. Astonishing delivery timescale from order to delivery from Shenzenaudio; China. Unpacked and plugged in. Switched on, did a bit of configuring. XLRs to AHB2 and MyTek BB. Played a few challenging tracks from Tidal, a range of flac 16 bit and MQA 24 bit. There is an improvement and it's not psychoacoustic phenomena. I know this because I can hear clear separation of overlaying backing vocals. This is none more so apparent on the MQA (digital master) New Order track Dreams Never End. Also, Arlo Parks "Hurt" is rendered with more resolution with her vocals being more detailed and pronounced. Not to forget, Andrew Weatherall‘s “Unknown Plunderer” which I label the “speaker killer“ So, it is an audible improvement. I think this is because the output voltage on the MyTek is much less than 4v - XLR. Hence, the Pre90 is helping to drag the most out of the AHB2s. On sensitivity, the Topping is i think about 40 Ohms while the AHB2 is over 500K so that makes it a good "match". I'm very happy with my combo at the moment. The entire hardware cost me less than my speaker cables - they're going out of the window soon too! I wonder if Amir would test them?????
 
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Jimbob54

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Just reporting back on my views on the Pre 90. Astonishing delivery timescale from order to delivery from Shenzenaudio; China. Unpacked and plugged in. Switched on, did a bit of configuring. XLRs to AHB2 and MyTek BB. Played a few challenging tracks from Tidal, a range of flac 16 bit and MQA 24 bit. There is an improvement and it's not psychoacoustic phenomena. I know this because I can hear clear separation of overlaying backing vocals. This is none more so apparent on the MQA (digital master) New Order track Dreams Never End. Also, Arlo Parks "Hurt" is rendered with more resolution with her vocals being more detailed and pronounced. So, it is an audible improvement. I think this is because the output voltage on the MyTek is much less than 4v - XLR. Hence, the Pre90 is helping to drag the most out of the AHB2s. On sensitivity, the Topping is i think about 40 Ohms while the AHB2 is over 500K so that makes it a good "match". I'm very happy with my combo at the moment. The entire hardware cost me less than my speaker cables - they're going out of the window soon too! I wonder if Amir would test them?????
So no A/B, unsighted or any other testing? Just plugged in and heard the improvement?
 

Docmoggy

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So no A/B, unsighted or any other testing? Just plugged in and heard the improvement?
Yes. Was obvious. I know others haven’t had the same experience and that may be because of DAC output voltage. I think over 4V and there probably isn’t a need.
 

Rottmannash

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