Topping A90 Headphone Amplifier Review

[Audimon]

Just booked my A90 on Amazon from SHENZHENAUDIO.
Will report on the volume knob, etc when I get it.

 

[imrul]

How many XLR outputs will the pre-90 have?

 

[ripvw]

Had my A90 for about a week now - very happy with it, no issues with volume knob or grounding. I'm running XLR from D90 Standard and then XLR to IN-8's - dead silent when it's supposed to be but can get real loud if I want it so. Also running low gain with Etymotic ER4SR earphones - volume setting anywhere from 11 o'clock to 1 o'clock depending upon source - sounds superb. Not sure if there would be any audible difference between the D50S/P50 feeding the Atom via RCA and this setup but I've finally got back to what I wanted - a balanced DAC and headphone amp/preamp with low output impedance. Neither the DX7s I owned or the DX7 Pro delivered on the low impedance. Thanks John!

Also, first time using California retailer Apos Audio and I must say I'm impressed. Great communication and A90 delivered ahead of schedule - I will be using them again. Like the D90 and A90 - Apos Audio is highly recommended...

 

[3125b]

It's funny, you were listening to the same song I'm now when reading this.

 

[GeorgeWalk]

Had my A90 for about a week now - very happy with it, no issues with volume knob or grounding. I'm running XLR from D90 Standard and then XLR to IN-8's - dead silent when it's supposed to be but can get real loud if I want it so. Also running low gain with Etymotic ER4SR earphones - volume setting anywhere from 11 o'clock to 1 o'clock depending upon source - sounds superb. Not sure if there would be any audible difference between the D50S/P50 feeding the Atom via RCA and this setup but I've finally got back to what I wanted - a balanced DAC and headphone amp/preamp with low output impedance. Neither the DX7s I owned or the DX7 Pro delivered on the low impedance. Thanks John!

Also, first time using California retailer Apos Audio and I must say I'm impressed. Great communication and A90 delivered ahead of schedule - I will be using them again. Like the D90 and A90 - Apos Audio is highly recommended...

View attachment 70123

I have the same setup with my Macbook pro and I love it.

Big high five also to Apos! I have ordered all my stuff from them and they are top notch. I ordered the A90 with express shipping. I emailed them when it looked like the DHL delivery date would be outside out their stated window. They said they would keep an eye on it. It arrived 1 day out of the window, but a couple of days ahead of DHL's original estimate. A couple of days later I got a refund for the shipping. I never had to follow up. They just did as they promised!

 

[Wazzupi]

Could there be a difference of any kind using a 4.4mm or XLR out from the same device like the Topping a90?

 

[Veri]

Could there be a difference of any kind using a 4.4mm or XLR out from the same device like the Topping a90?

No way, it's the same output wired to a different connector..

 

[saadi703]

Here is the photo of my D90 + A90 stack which now completed after I received my Topping A90 yesterday. I was using Monolith THX 887 before as main amplifier. I got it within 6 days from the order (including 2 extra days it took after arriving in my country as it was just sitting (Thanks to DHL who is taking 3-5 days extra after the shipment has arrived in my country due to current COVID-19 situation). Ordered from Shenzhenaudio through aliexpress and these guys are always pretty fast with order processing and shipping. I order my Topping D90 through them as well back in early January.

 

[GeorgeWalk]

Here is the photo of my D90 + A90 stack which now completed after I received my Topping A90 yesterday. I was using Monolith THX 887 before as main amplifier. I got it within 6 days from the order (including 2 extra days it took after arriving in my country as it was just sitting (Thanks to DHL who is taking 3-5 days extra after the shipment has arrived in my country due to current COVID-19 situation). Ordered from Shenzhenaudio through aliexpress and these guys are always pretty fast with order processing and shipping. I order my Topping D90 through them as well back in early January.

View attachment 70300

Beautiful photo. Do you do professional work? Topping should hire you for their promo stuff.

 

[Ddd]

-Why RCA input measures better?
A: According to Douglas Self's small signal book, balanced connection is inherently more noisy than unbalanced. The benefits of balanced connection is to avoid interference and ground related issue. In ideal condition, RCA input outperforms XLR in.

-Atom didn't have the noise with RCA but A90 has
A: This is very common with a device that has ground connection. This is classic ground related issue. It's not severe enough to be a ground loop but it's there. Also SMPS needs ground return path to work the best because of leakage current. So RCA connection + separated two grounding route is the cause of the issue. XLR is recommended.

-Will L30 have the issue?
A: Similar to Atom, external transformer based AC power supply is used. This eliminates SMPS's leakage current, traditional transformer magnetic interference, also the earth connection. Hence its unbalanced connection be more robust to interfacing to other devices. Less than 100nV(70nV typical) of mains noise is what you will get.

Yeah, using D90 MQA + A90 now

Just did a try today and found out whenever I connect the RCA cable for D90 A90, the unit will suffers from a constant ground loop noise. M gain slightly audible while H gain is the most obvious.
The noise only go away after the RCA cable connection between both device is removed.

As expected from two device that utilised the Earth connection.

To solve this issues, I lifted the Earth wire inside the IEC connector of A90, guess this ensures the A90 will only ground through D90 by then
And the RCA issues is fixed, no more audible noise.

So does this means A90 will suffers ground loop issues all the time if it is paired with a DAC that utilised the Earth connection?

Just a question @JohnYang1997 , is it fine to do so? does it degrade the performance or post any safety issues?
Because i saw your previous comment mentioned lifting the Earth wire is not recommended.

And was wondering why the XLR section doesn't suffer this ground loop problem while only the RCA section does??

 

[Veri]

And was wondering why the XLR section doesn't suffer this ground loop problem while only the RCA section does??

XLR standard was made to have common mode rejection, the signal is overlaid in positive and negative phase cancelling out most forms of benign and ground noises. RCA standard is much more prone to Earth noise but on short cables it can be inaudible. It depends on which devices you are connecting.. personally on most of my dac+amps even on RCA I had no noise but other people have ground noise very quickly.

In any case, it's one of the reasons why XLR way of connecting is highly recommended whenever possible.

 

[JohnYang1997]

Yeah, using D90 MQA + A90 now

Just did a try today and found out whenever I connect the RCA cable for D90 A90, the unit will suffers from a constant ground loop noise. M gain slightly audible while H gain is the most obvious.
The noise only go away after the RCA cable connection between both device is removed.

As expected from two device that utilised the Earth connection.

To solve this issues, I lifted the Earth wire inside the IEC connector of A90, guess this ensures the A90 will only ground through D90 by then
And the RCA issues is fixed, no more audible noise.

So does this means A90 will suffers ground loop issues all the time if it is paired with a DAC that utilised the Earth connection?

Just a question @JohnYang1997 , is it fine to do so? does it degrade the performance or post any safety issues?
Because i saw your previous comment mentioned lifting the Earth wire is not recommended.

And was wondering why the XLR section doesn't suffer this ground loop problem while only the RCA section does??

A90 will use the ground from the upstream as the earth connection. Is it safe? I think for the longest time I don't think anything would happen. But I will not be responsible for any damage. Because I still recommend using XLR. From my recommendation, make sure one of the devices is earthed.
In terms of performance, shorter rca cable would help a lot. Then if you cannot hear any noise then it's fine. Listening is ultimately what matters right?
Balanced connection itself is immune to these kind of issues inherently and it's the sole reason why it's there.

 

[odyo]

Nope, I used a separated switching power supply, 5V 2A. My PC with an overclocked 5820K and a Vega64 is very noisy, I know that and I am very sensitive to this kind of noise, but the strange part was that 2 DACs based on AKM chips didn't have the hiss, 3 with ESS did instead. Anyway the electrical tape resolved 95% of the noise coming from the DAC, and the XLRs solved the other 5%, through headphones I cannot hear anything, now I only have a bit of noise coming from my speakers' woofers connected to an Anaview module (this wasn't there with a JDS Atom, it is there with the A90 connected through RCAs). I will use XLRs also on it and, hopefully, problem solved even there

I have sbx ae5 soundcard in my pc. Ess based dac in it. Pc is heavily overclocked 2080 and 9900k + lots of coil whine. However my soundcard manages 100% clean output to all kind of headphones at every gain level. But my speakers has lots of hissing issue i dont know if its soundcard or power strip causing this. Really good job on headphone output though lots of nasty stuff going on inside pc case and soundcard heats up a lot. Headphone output is always completely pure. Psu is Corsair rm1000i it might have an effect.

 

[saadi703]

Beautiful photo. Do you do professional work? Topping should hire you for their promo stuff.

Thanks so much. I am a Civil Engineer by profession but I am a passionate photographer as well and product photography is one of genres of photography that I really enjoy. Yep, Topping should hire me lol

 

[saadi703]

This noise floor discussion with regard to RCA connection made me curious so I tried both shorter and longer RCA cables between D90 and A90 and I can not hear any noise even in high gain at max volume level. I am using USB connection (same cable that came with D90) to D90 from my PC.
RCA cables are also cheapo cables (shorter one came with my iFi micro iDSD black label and longer one is just cheap generic RCA cable).

 

[Veri]

Grounding noise very much depends on your set-up, in the right circumstances it will be a pain, in others it won't ever be an issue. VERY circumstantial.

 

[Racheski]

One of my favorite reviewers has posted about the A90. I love when he says, “ehn-gin-eeer” when talking about John Yang. He sounds like Ahnold!

 

[PCZ_97]

Hi guys just a quick simple question for the owners of the Topping A90 amp, does your amplifier also emit a very very little noise (typical psu noise, like a whistle,99% coming from the psu) if you approach it with your ears, like from close distance? It’s normal or my unit is faulty/noisy?

 

[hmscott]

Hi guys just a quick simple question for the owners of the Topping A90 amp, does your amplifier also emit a very very little noise (typical psu noise, like a whistle,99% coming from the psu) if you approach it with your ears, like from close distance? It’s normal or my unit is faulty/noisy?

Unfortunately my A90 / D90 MQA is fed from and sitting on top of a Ryzen Desktop PC, so the PC fan noises override the noise you are describing.

Which end of the A90 is the noise emitting? Near the power cord area? Does the sound transmit through the cables? What do you have the A90 power cord plugged in to? Wall, power strip, power conditioner?

I'll check later when I can drive it with my FiiO M15 - need a cable, USB-C to USB-B, then I can turn my PC off. Perhaps it will make the sound when idle, I'll try turning off the PC later and leave on the A90 / D90 MQA.

Good job noticing that tiny noise

 

[PCZ_97]

Unfortunately my A90 / D90 MQA is fed from and sitting on top of a Ryzen Desktop PC, so the PC fan noises override the noise you are describing.

Which end of the A90 is the noise emitting? Near the power cord area? Does the sound transmit through the cables? What do you have the A90 power cord plugged in to? Wall, power strip, power conditioner?

I'll check later when I can drive it with my FiiO M15 - need a cable, USB-C to USB-B, then I can turn my PC off. Perhaps it will make the sound when idle, I'll try turning off the PC later and leave on the A90 / D90 MQA.

Good job noticing that tiny noise

Thanks for the reply, the noise is audible from outside the unit, both in the power cord area and in the rest, but you must bring your ear close to it and be in a quiet room, otherwise being very light it is not easy to notice. The noise does not spread through the cables from what I could see and hear, through XLRs are completely silent while if I go from RCA to M gain at high volume (3/4 of pot volume) I can hear some noise floor (it could also be the famous hum of the ground loop you guys were talking about in the previous posts). Both the D90 and the A90 are plugged in a filtered EMI/RFI power strip that is connected to wall. The D90 is fed by USB, but I tried in Optical too, the “hum” noise is exactly the same on RCA, so I think it’s actually ground loop noise and not source dependent, my source is actually surprising silent and interference free from what I can see, If I do the same test but with DAC off, I can’t hear any “hum” noise even at max volume on H gain on my headphones. I think this case of “hum” ground noise is pretty normal and easily remediable with a ungrounded high quality Power cord.