Topping A90 Headphone Amplifier Review

[TheTalbotHound]

Honest question from someone just starting with headphones. What is the audible difference between a a90 and lets say a benchmark hpa4?

From what i've heard A90 has less opamp glare. Hard to say if that can be confirmed objectively though since Amir does not show IMD measurements for most amps, including A90.

 

[Veri]

From what i've heard A90 has less opamp glare.

Mine never glared at me

 

[TheTalbotHound]

Really do wish amir showed IMD measurements for Headphone amps though.

 

[nimar]

@JohnYang1997 Hey,
Any reason to prefer pairing the A90 with the D70s vs the D90 or vice versa

I currently run the d90 directly into active speakers, and have the d70s / a90 in the post.

Then will either have the d90/a90 in my office with active speakers / headphones and the d70 into a power amp / passive speakers. Or swap the d70/d90 around.

My one concern is the d70s’ 5V balanced output as my power amp (purifi eval1) goes to max with only 1.5V.

Am leaning towards the d70s/a90 for the office even if the stack won’t look as nice (different sizes). But aesthetically the d90/a90 go better together, and I would imagine were designed with each other in mind.

 

[Inkey31]

Hey will a 18V power supply, like the one found in the SP400 do better in over power delivery then the A90 which is a 15V power supply?

 

[Inkey31]

Can anyone explain how to read this thing? How does this translate into Watts?

 

[nimar]

Can anyone explain how to read this thing? How does this translate into Watts?

last column is in watts

very loud -1.6W
painful - 5W

 

[kurosawa]

The topping a90 hpa has more power then the rme adi-2 pro headphone in balanced mode, so it should be able to drive the iFi IESL electrostatic energizer.

Rme adi-2 pro:
Balanced Phones mode
As before, but:
• Output levels at 0 dBFS: Hi-Power off +13 dBu (3.46 V), Hi-Power On +28 dBu (19.5 V)
• Output impedance: 0.2 Ohm
• Signal to Noise ratio (SNR) @ +28 dBu: 120 dB RMS unweighted, 123 dBA
• Signal to Noise ratio (SNR) @ +13 dBu: 118.4 dB RMS unweighted, 122 dBA
• Output level at 0 dBFS, Hi-Power On, load 150 Ohm or up: +28 dBu (19.5 V)
• Output level at 0 dBFS, Hi-Power Off, load 8 Ohm or up: +13 dBu (3.46 V)
• Max power @ 0.001% THD: 2.9 W per channel

Topping a90:

 

[RHO]

How does the A90 perform in low gain? Is it usable when driving IEMs? How much range would I have on the volume control (single ended output)?

 

[Veri]

How does the A90 perform in low gain? Is it usable when driving IEMs? How much range would I have on the volume control (single ended output)?

-Great!
-Yes, sure
-can go to 12 o'clock depending on the IEM, and depending if you're using balanced input or SE input.

 

[RHO]

-Great!
-Yes, sure
-can go to 12 o'clock depending on the IEM, and depending if you're using balanced input or SE input.

Considering an A90 + Gustard X16 combination. So I'll be using the balanced in that case.

 

[Veri]

Considering an A90 + Gustard X16 combination. So I'll be using the balanced in that case.

You can attenuate the volume on the X16 a little. At least -04 like in Amir's review. But you could go lower up to say -10 or so to allow for smoother volume range on A90

 

[RHO]

You can attenuate the volume on the X16 a little. At least -04 like in Amir's review. But you could go lower up to say -10 or so to allow for smoother volume range on A90

Didn't think of that. Good point. Thanks!
Still considering different combos but the Topping + Gustard looks like it has everything I want.

 

[hmscott]

How does the A90 perform in low gain? Is it usable when driving IEMs? How much range would I have on the volume control (single ended output)?

I've found on the most sensitive IEM's / headphones it helps to reduce the drive from the Topping D90 MQA DAC - take it out of DAC mode and adjust the output from -3.0dB to -30.0dB.

Then I have more control over the volume on the A90 not only for sensitive IEM's but also for any headphone that normally runs in L/M Gain, and then I can put them in M/H Gain to play with how it affects the sound.

Then adjust the D90 MQA a bit more to drive more / less as I need to.

I don't detect any reduction in resolution or fidelity between 0.0 and -30.0dB, simply lower output to the A90.

Except for low sensitivity IEM's I now prefer to keep the D90 MQA in DAC mode for most of my use - so I am not tempted to twiddle with the D90 MQA variable output - as it can be distracting me from my listening time.

Update: FYI, I received a marketing email from APOS about various products, and the last product is a comparison chart between the Topping A90 and the SMSL SP400:
https://apos.audio/blogs/news/smsl-sp400-vs-topping-a90-comparison-chart

 

[RHO]

The A90 would be really the top of the price range that I'm willing to spend on an HP amp. Luckily it's also a very, very good one.
It's the pre-amp functionality that makes me want this more than the A30pro. (thinking about some active near-filed monitors on my desk)

 

[yanava]

Hi bboris77.
If you plan to buy it, I would not worry about it, it is a great amplifier whose sound does justice to its specifications. It does not affect the volume adjustment at all and the feel of the knob is very good. It just has a little slack that would be better without it, that's true, but nothing more.

The other day when I took it apart, I got the impression that that clearance, or at least some, is due to the potentiometer itself and not the knob assembly. This is pressurized with a plastic adapter to the potentiometer shaft with a slot. Anyway, I will check it again and I will comment.

Can you please deatil the tools you used to take it apart? I want to see mine and the knob is basically the one thing standing in the way! Thanks!

 

[VeerK]

The A90 would be really the top of the price range that I'm willing to spend on an HP amp. Luckily it's also a very, very good one.
It's the pre-amp functionality that makes me want this more than the A30pro. (thinking about some active near-filed monitors on my desk)

thats how I use the A90, headphone amp and speaker preamp

 

[mrbungle]

I have exactly the same issue. A90 + MOTU M2. Hearing music from nearby radio station. Balanced XLR input and output. Coiling the headphone cable and holding it tight removes the interference. No issue with single-ended output. Switching gain to high reduces the noise, no difference between low and medium gain. Disconnecting XLR input does not reduce the noise. Did you solve your issues?

If I understand your question correctly (apologies if I'm not), the signal is from a very powerful AM radio station that it was about 1.5-2 miles from me. I've had a D90 for a few months now, and never had this issue while using my Drop AAA 789 (or other amplifiers). I only noticed it when I bought the A90. I can hear the radio station very faintly through the headphones when my DAC is not playing anything.

 

[RHO]

thats how I use the A90, headphone amp and speaker preamp

Any issues with chann

You can attenuate the volume on the X16 a little. At least -04 like in Amir's review. But you could go lower up to say -10 or so to allow for smoother volume range on A90

I guess this would also help with solving the channel imbalances at the bottom usable of the volume range?

 

[mrbungle]

I have exactly the same issue. A90 + MOTU M2. Hearing music from nearby radio station. Balanced XLR input and output. Coiling the headphone cable and holding it tight removes the interference. No issue with single-ended output. Switching gain to high reduces the noise, no difference between low and medium gain. Disconnecting XLR input does not reduce the noise. Did you solve your issues?

Answering my own question, couple of Ferrite rings fixed it.