Topping A90 Discrete Review (Headphone Amp & Preamp)

[Veri]

I use this on my coax SPDIF:

SPDIF iPurifier2 by iFi audio | Digital Optical and Coax Audio Signal Optimiser

Refresh your SPDIF audio signal. The SPDIF iPurifier2 goes into your SPDIF port and solves audio caused by poor quality signal transmission. TV, games and movies sound transformed.

ifi-audio.com

Hmmm. Why, though. I guess it doesn't harm anything. But I believe this older review proves it to be basically useless:

Review and Measurements of iFi iPurifier S/PDIF Digital Audio Filter

This is a detailed measurement and review of iFi iPurifier. This is a device that is advertised to clean up your coax S/PDIF signal from all ills including the common flu to audio distortions. It is a tiny little box the size of a thumb drive: Not shown is the fact that it actually needs...

www.audiosciencereview.com

 

[SoNic]

That was version 1, alleged they improved it. It provides galvanic isolation at a minimum.

Jitter effect is hard to evaluate. Some DAC chips are more prone to that than others. For example, the ESS chips have a whole ASRC block inside that deals with jitter.

ESS Sabre32 DAC - Apogee Electronics

Apogee includes the ESS Sabre32 DAC in many of their USB, Thunderbolt and iOS interfaces such as Duet, Ensemble, Quartet and Symphony I/O.

apogeedigital.com

Now, some manufacturers have DSP chips in front of the DAC chips, so there also the jitter is eliminated. For example, Schiit Audio uses Analog Devices SHARC DSP. My Denon AVR uses similar Analog Devices SHARC DSPs (multiple).
Older DACs had FIFO buffers to deal (with more or less success) with that issue too.

 

[mocenigo]

What would make this Topping A90 (as w/most tested hw) more usable is to either have:
* Both rear XLR/RCA outputs simultaneously available, or at least

Is this not possible?

Roberto

* One of the rear (XLR or RCA) outputs simultaneously available w/one of the front headphone outputs.

 

[escalibur]

What is the current situation with -5 error code? Have any of you noticed some new reports of faulty units? I'm still tempted to update my A90 to this model.

 

[Music1969]

What is the current situation with -5 error code? Have any of you noticed some new reports of faulty units? I'm still tempted to update my A90 to this model.

I just got one and can't reproduce this error with single ended output

So if you get a 2023 production unit i think its all fine

Gorgeous looking amp

 

[mocenigo]

The first 10db steps are 0.5, -80db steps are 2db, and the middle steps are 1db.

But the numbers are not actually related to Db, right?

 

[Phony846]

All good with your replacement unit ?

Yes so far.

 

[Music1969]

Yes so far.

Nice, I think all current production units are generally problem free now.
I bought a unit last month and tried to reproduce this with 6.3mm headphones plug and it was fine.

My rule with Topping products is - wait 6 months after release before you buy !

 

[shrimp_dude]

My rule with Topping products is - wait 6 months after release before you buy !

I think that's a safe rule to follow with all the chinese companies (Topping/SMSL/Gustard/etc). Always firmware and other updates following the releases to fix problems.

 

[Music1969]

To be honest it is probably a good rule for any company, not just Chinese

I had to return a brand new Chord Hugo to the UK

 

[simplywyn]

To be honest it is probably a good rule for any company, not just Chinese

I had to return a brand new Chord Hugo to the UK

Every company uses Chinese components, so it's all made in China even the ones "made in USA" are just US made cases with Chinese components.

 

[zhgutov]

Every company uses Chinese components, so it's all made in China even the ones "made in USA" are just US made cases with Chinese components.

Some companies like Lake People use (or maybe used in the past) components made in Germany. Texas Instruments is one of such manufacturers.

 

[simplywyn]

Some companies like Lake People use (or maybe used in the past) components made in Germany. Texas Instruments is one of such manufacturers.

Texas instruments makes most of their stuff in China. They entered China in 1986 and have research centers in shanghai, beijing, chengdu... etc lol

 

[zhgutov]

Texas instruments makes most of their stuff in China. They entered China in 1986 and have research centers in shanghai, beijing, chengdu... etc lol

"most" - is the key word here, I suppose

 

[simplywyn]

"most" - is the key word here, I suppose

Most, meaning probably all. Everything is made in China, you can't avoid it. The small resistors they use to populate their board? made in china. Most of the micro caps they use? Probably made in China.

The problem isn't because they are made in China. The problem is that these tiny pieces of electronics are CHEAP and offer zero performance gains if they are made in Germany or made in Japan. So why not buy the cheapest since they offer zero difference in build quality, and those are made in China.

That's the major issue with bringing work back to America. You have basically a shit ton of tiny parts, that offer zero performance difference, that you simply need to create a circuit, but instead of it costing 25cents, it costs a dollar here. That's what kills it, and they have to invest a huge amount of money here to get costs down (which is more money). It's a catch 22

 

[zhgutov]

offer zero performance gains if they are made in Germany or made in Japan

As I know, this is not about the performance. It was about the cost and consistency. Domestic manufacturing may be cheaper in some cases. I'm not sure if this is still the case.

However, the companies which use that electronics may use its own additional QC for special purposes.

 

[Music1969]

Anyway, A90 input impedance is found here, and it is stated for balanced, it is 2K and 10K for unbalanced. If this is the same too for A90d, then there shouldn't be an issue of impedance mismatching.

Yikes that is very low input impedance for balanced

Need to pay close attention to DAC matching

 

[Music1969]

I asked the same question (since it is hard to search this up among 10000k comments).
M400 xlr ouput is 10k ohms.

Topping A90: 2kOhm for balance input. 10k for unbalanced.

So far Gustards data for dacs A18 or X16 was correct so far, with only low deviations of 50 ohms.
Output impedance 100 ohms (around 150 measured)
XLR Output level: 4Vrms(VOLUME 00dB)
Output impedance 300 ohms (around 350 measured).

Smsl SU-9 RCA output is ~120 and for xlr it is 370 ohms.

Is similarly low for topping D90 I remember.

Can match and mix them freely. Will only lose negligible audio level. Simply get short interconnect cables; 30 cm or so.
Only careful about the M400 Dac.

Hi your post is mixing input and output impedances, so it is not clear

Are you sure the Topping A90D input impedance is 2000 ohm for XLR ?

Where did you get this information?

 

[staticV3]

Are you sure the Topping A90D input impedance is 2000 ohm for XLR ?

Where did you get this information?

https://www.audiosciencereview.com/...eview-headphone-amp-preamp.35114/post-1272180

 

[Music1969]

https://www.audiosciencereview.com/...eview-headphone-amp-preamp.35114/post-1272180

Thanks I did find that yesterday.
And thanks to the guy that measured.

That is abnormally low input impedance but not an issue if DAC output impedance is (actually) < 200 ohms (XLR)