Topping A90 Headphone Amplifier Review

[Mr:River]

Could you try using a RCA to XLR cable with XLR pin 1 connected to RCA shield? Or is this of any benefit in ground loop situations?

Good question.
I am about to receive my A90 and I plan on making an RCA / XLR connection.
I have a RCA D10s >> XLR >> A90
Is this the best connection?
I will use my HE400i XRL

 

[Veri]

Good question.
I am about to receive my A90 and I plan on making an RCA / XLR connection.
I have a RCA D10s >> XLR >> A90
Is this the best connection?
I will use my HE400i XRL
View attachment 93646

I own some of these kind of cables and they work fairly well, yes.

 

[mocenigo]

Ayyyyyy!

And if I am not mistaken the L30 is just "half" of a A90, only unbalanced in and out, so its measurements should roughly be 3db worse than the A90 and that's it?

 

[Lero]

And if I am not mistaken the L30 is just "half" of a A90, only unbalanced in and out, so its measurements should roughly be 3db worse than the A90 and that's it?

Singol ended amplification should be the same, something less premium in the circuits and in the power supply that is outside.

 

[mocenigo]

It is a factor two

In voltage. Which means roughly 9.5Db,

 

[mocenigo]

The best combos right now seems to be

E30/L30 for non balanced
QXD1+A50s (if it will be released) if you want balanced on budget not needing preamp
QXD1 + A90 if you want best balanced amp but still keeping an eye on budget, and having preamp
SGD1 + A90 if you want best balanced amp and dac, bluetooth, remote and preamp
D90 + A90 if you want to go bal*s deep and you like the look of a matching stack

D90 + L30 is perfect also if you need bal out for power amps, you live well with unable out to the L30 to SE cans, and want some partial matching in looks.

 

[Atanasi]

Singol ended amplification should be the same, something less premium in the circuits and in the power supply maybe

Note that L30 has a floating power supply, unlike A90 which requires a ground connection for intended operation, so L30 is less likely to cause ground loops when you have unbalanced interconnections. Therefore, L30 is simpler to install in many systems.

 

[Lero]

Note that L30 has a floating power supply, unlike A90 which requires a ground connection for intended operation, so L30 is less likely to cause ground loops when you have unbalanced interconnections. Therefore, L30 is simpler to install in many systems.

I know my comment was about final result performance.

 

[Mr:River]

New Times....
Micro-nano.

 

[Mr:River]

@JohnYang1997

As an A90 designer you know him very well, could you help?
I have a hearing loss in my right ear, this is affecting my phone channel balance, I want to know in your knowledge how I can put a balance control on the XLR of the A90 so that I can better equalize the sides of my phone.

 

[Veri]

@JohnYang1997

As an A90 designer you know him very well, could you help?
I have a hearing loss in my right ear, this is affecting my phone channel balance, I want to know in your knowledge how I can put a balance control on the XLR of the A90 so that I can better equalize the sides of my phone.
View attachment 93809

Some good DACs have a balance configuration in the XMOS control panel. I would recommend for you to do this on the DAC side.

 

[Mr:River]

Some good DACs have a balance configuration in the XMOS control panel. I would recommend for you to do this on the DAC side.

My dacs D10s, does it have this feature?

 

[Jestercow]

Mine died yesterday after only a couple months of use. Sat down to my computer to relax and my right channel had either very low or no sound. checked the headphone connections and they were fine, went to unplug and replug in the 1/4" and the right channel had a incredibly loud "POP!" as the jack went in (hoping it did not damage my Focal Elex). I also grabbed a pair of cheap IEMs and had the same experience. Left it turned off and unplugged overnight, same issue today. Happened with both the 1/4" and XLR cable. I've reached out to Apos and am hoping they can get me sorted

Update: Apos is RMA'ing my unit, I asked if they could fill me in on what had happened to mine as I seem to have been the only person who had this happen. Anyone have any clue what could have caused this or what even happened?

 

[Veri]

Update: Apos is RMA'ing my unit, I asked if they could fill me in on what had happened to mine as I seem to have been the only person who had this happen. Anyone have any clue what could have caused this or what even happened?

If you heard a 'Pop' followed by broken behaviour, it seems that you got a lemon. Bad luck

 

[777]

??????? What is this ?

 

[ayane]

Yeah, that's the only quirk of the A90 - the low input impedance. For what it's worth, the low-impedance inputs help the A90 achieve its tremendously low noise floor, so it's more of a trade-off than a downside.

If you have a good DAC with a low output impedance, this isn't a problem, but putting most DACs in front of the A90 will result in slightly impaired DAC performance. This isn't really a problem with most well-designed DACs, but it's still going to be measurable as a few dB lost in end-to-end SINAD. Regardless, for most people, it's not going to be a problem at all, because what you may potentially lose is well beyond the threshold of audibility.

 

[777]

Yeah, that's the only quirk of the A90 - the low input impedance. For what it's worth, the low-impedance inputs help the A90 achieve its tremendously low noise floor, so it's more of a trade-off than a downside.

If you have a good DAC with a low output impedance, this isn't a problem, but putting most DACs in front of the A90 will result in slightly impaired DAC performance. This isn't really a problem with most well-designed DACs, but it's still going to be measurable as a few dB lost in end-to-end SINAD. Regardless, for most people, it's not going to be a problem at all, because what you may potentially lose is well beyond the threshold of audibility.

So, 20 ohm and 40 ohm are the correct values ?

 

[Atanasi]

So, 20 ohm and 40 ohm are the correct values ?

They are output impedances for the pre-outs. You have some version of the table with a typo.

 

[w1000i]

No.

So what about desktop amplifiers

 

[mocenigo]

@JohnYang1997 Any plan to use Gallium nitride (GaN) MOSFET in a headphone amplifer ?

Why should they be used? There could be an advantage for Class D amps because of the faster switching and shorter dead time, but currently they have higher thermal noise. So for the moment for the highest measurable performance one should stick to Silicon for amplification circuits (or accept higher - but still inaudible - noise to simplify circuitry and reduce size, as Orchard has done). Currently, power supplies seem the best place to deploy them for audio applications - improving efficiency and reducing power supply footprint.