Topping A70 Pro HP & Preamp Review

[LeShog]

This is a review and detailed measurements of the Topping A70 Pro balanced headphone amplifier and preamplifier. It was sent to me by the company and costs US $499.
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Like its companion DAC, the D70 Pro Sabre, the A70 Pro sports the gorgeous and highly responsive display (which can be set to above or graphic VU and spectrum analyzer). While it was nice to have in the DAC, it is essential here given the extensive functionality of this amplifier. Every input and output is selectable independently and in combination. If you need more inputs, you can get the optional Ext90 extension using the compatible connector:

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Nice to see trigger in/out fully standard on Topping products.

Volume control is implemented using stepped relay to provide perfect channel matching. Normally this functionality comes at a cost of slow volume control response and noise induced into the audio path. Not here. Volume control could not be more responsive with very wide range of 100 dB. While you hear the mechanical relays if you get close to the unit, I could not detect any interruption or noise in the audio path. This is a superb implementation!

Microprocessor controlled protection circuit watches over the conditions of the device and shuts it down in extreme condition. What I like about it is that it auto recovers quickly and without user intervention. Firmware input support is provided for future refinement of this functional if needed.

Note that the extensive functionality makes the device a bit harder to use. You can easily get yourself in modes where you are not getting sound and wondering why. In this case, the level display is super helpful. As is the remote which automates some settings such as gain and RCA vs XLR input. You can also create two provides and recall them using C1 and C2 switches.

There is a ton of functionality here that would take me days to test. So I made a choice to make abbreviated preamp tests and then balanced headphone output.

Topping A70 Pro Preamplifier Measurements
Let's start with balanced input and output with variable volume control:
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FFT display shows no recognizable distortion spikes other than the signal generator out of my audio analyzer! We are basically bound by signal to noise ratio which sets the overall SINAD to 121 dB (6 dB better than transparency under all conditions). Switching to RCA in/out surprisingly upped the performance a bit:
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Balanced mode does provide more output though:
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Finally here is our SNR:
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Headphone performance should be highly indicative of preamp so let's get into that.

Topping A70 Pro Headphone Amplifier Measurements
As noted, I limited my tests to XLR balanced headphone output. Let's pump 4 volts into it and adjust volume to get 4 volts out:

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We get the same great performance as we did in pre-amp mode. RCA input this time did cost us a bit as it normally does:
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These are superb measurements, albeit just a hair off from best there is due to lack of an ultra low gain mode that some other Topping products have:
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Noise performance shows why XLR input is a bit better:
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50 mv output mode delivers near top of the class performance:View attachment 285108

Frequency response is exceptionally flat:
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Multitone performance is superb:
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Power is just about everything in headphone amplifiers so let's see how we do there:
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Wow, we have over 8 watts driving dual channels simultaneously at 32 ohm! Even low gain with its superbly low noise delivers 2 watts.

Changing the load from 600 ohm down to punishing 12 ohm shows superb ability to hold up the output voltage and hence keep delivering more and more power:
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This is in entirely different class than any headphone amplifier I have tested!

I usually don't run the channel matching test with R2R relay volume controls but ran it here to show the superb implementation:
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The dashed blue line shows deviation between the two channels. As you see, all the way down to the limit of -100 dB it remains at 0. Absolutely great!

Topping A70 Pro Headphone Listening Tests
I started testing my with everyday, low impedance and difficult to drive Dan Clark Stealth headphone. Even in low gain the A70 Pro drove these to almost ear bleeding levels and superb dynamics. Switching to high gains provided essentially infinite headroom and extra volume. Try as I might, I could not dare going past -15 dB. With other headphone amps, I could hear distortion at the maximum volume (or not enough volume). Both of those limits are long, long gone with the A70 Pro. You have so much power that any distortion or problems are clearly that of the headphone.

Switching for Sennheiser HD650 once again showed the incredible power reserves of the A70 Pro, allowing these headphones to shine with incredible detail and dynamics. There was no hint of any background noise and as noted, volume control was smooth, responsive and delight to adjust.

Conclusions
With A70 Pro, Topping pushes boundaries on multiple fronts. The device is gorgeous to look at, and informative and highly responsive to use. Power is increased to where it needs to be to drive even the most difficult to drive headphone as if it is a walk in the park. Measured performance is state of the art providing assurance of transparency. Subjective testing results couldn't be better. For a person who pushes amps to their max to see and hear the limits, I was out of a job with A70 Pro! There is not a negative here of any sort or shape. Yes, $499 is the price to pay. I suggest saving up money until you can afford to buy one if you are a serious headphone listener.

It is my pleasure to recommend the Topping A70 Pro. I am not sure how anything better can be designed but I am sure Topping will keep working at it!

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

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

I have a jds atom 2 with Audeze lcd2c (70 ohm with 101 db/mw sensitivity), but still I find the sound, especially on classical, to be weak, like I needed more dynamics; a bit of context: I listen to, normally, 55-65 db depending on the mood, so I would say pretty low. I use the high gain to have more dynamics as possible, but still I feel I’d need to turn the volume knob up to open my cans, but don’t want to, I’m fine with my volume. I want a more present, muscular sound, so more dynamic (I guess?) without adding volume. I don’t understand how dynamics in audio works and tried to search over for some papers/topics, but couldn’t find any suitable, maybe you can address me to some thread of yours? I tried to look, but did not find in the forum. Do you believe a powerful amp like this one could fix this problem for me? Thank you.

 

[Rhamnetin]

I have a jds atom 2 with Audeze lcd2c (70 ohm with 101 db/mw sensitivity), but still I find the sound, especially on classical, to be weak, like I needed more dynamics; a bit of context: I listen to, normally, 55-65 db depending on the mood, so I would say pretty low. I use the high gain to have more dynamics as possible, but still I feel I’d need to turn the volume knob up to open my cans, but don’t want to, I’m fine with my volume. I want a more present, muscular sound, so more dynamic (I guess?) without adding volume. I don’t understand how dynamics in audio works and tried to search over for some papers/topics, but couldn’t find any suitable, maybe you can address me to some thread of yours? I tried to look, but did not find in the forum. Do you believe a powerful amp like this one could fix this problem for me? Thank you.

Aside from raised volume, the only other solution I can think of is equalizing your LCD-2C, perhaps giving it a more Harman like bass response and 2-4.5 KHz response.

 

[staticV3]

Yeah, a more powerful Amp won't change anything.

 

[staticV3]

@LeShog what operating system and music player software do you use?

 

[LeShog]

@staticV3 I suspected that, thank you. Yeah I wanted to equalize, but I run music through my apple phone right now and it can’t be equalized. I use qobuz as main source, filed a request to add a peq in app. Since then I guess I am going to get out my laptop, a mac. I have an old version of Audirvana installed, but it doesn’t have eq. Any advice on a practical peq for mac os to use with qobuz? I’ll just look in the right section in case when I have time..

 

[staticV3]

@LeShog how does audio currently get from qobuz on your iPhone to the Atom Amp 2?

 

[LeShog]

I am using an ifi xdsd gryphon (portable dac/amp with battery) as dac, but planning to get topping e50 dac as it’s more practical: I don’t need to remember to charging it and I can stack it under my jds atom 2. I really liked how it performed on Amir’s tests, it seems to be pretty close to perfection. Also this way my gryphon will always be ready to be taken on the go, with enough juice: I recently bought some iems (truthear hexa) and want to bring it with me. I had some tws, but couldn’t listen to classical, it was way too distorted and crowded, very dirty. The other genres were ok though.

 

[staticV3]

@LeShog Consider buying a Qudelix 5K instead of the E50.
You can load oratory's EQ preset for the LCD-2C directly onto it, then use either Bluetooth or USB to connect your MacBook or iPhone for audio playback.

There's an App with tons of useful features for configuring connectivity and power management and you can even configure it from your MacBook.

 

[LeShog]

@staticV3 wow ok thank you, I’ll check it out

 

[JK002]

A DAC Topping D70 for Octo was added to the A70 pro Topping, while I'm testing, first I made 3 pieces of cables for the trigger from bluesound to the D70 and then to the A70, then to the nc502mp, switching on without any problems, I also tried different filters on the D70, but I can't hear the difference more precisely it seems to me that it is then that it is not, but what are the subjective impressions of the DALI Oberon 5 speakers
both devices are the same in color, it doesn't look like that in the photo, I don't know why, maybe the daylight comes from the left

 

[Gymboy]

A DAC Topping D70 for Octo was added to the A70 pro Topping, while I'm testing, first I made 3 pieces of cables for the trigger from bluesound to the D70 and then to the A70, then to the nc502mp, switching on without any problems, I also tried different filters on the D70, but I can't hear the difference more precisely it seems to me that it is then that it is not, but what are the subjective impressions of the DALI Oberon 5 speakers
both devices are the same in color, it doesn't look like that in the photo, I don't know why, maybe the daylight comes from the left

Its hard to hear difference between filters, I left it on F5 " no oversampling " feels least digital and little softer on the edges, at least to my ears.

 

[Jimster480]

I have a jds atom 2 with Audeze lcd2c (70 ohm with 101 db/mw sensitivity), but still I find the sound, especially on classical, to be weak, like I needed more dynamics; a bit of context: I listen to, normally, 55-65 db depending on the mood, so I would say pretty low. I use the high gain to have more dynamics as possible, but still I feel I’d need to turn the volume knob up to open my cans, but don’t want to, I’m fine with my volume. I want a more present, muscular sound, so more dynamic (I guess?) without adding volume. I don’t understand how dynamics in audio works and tried to search over for some papers/topics, but couldn’t find any suitable, maybe you can address me to some thread of yours? I tried to look, but did not find in the forum. Do you believe a powerful amp like this one could fix this problem for me? Thank you.

This amp could help as it may deliver more current which your planar may need.

 

[LeShog]

@Jimster480 thank you, I equalized my headphones and now feel like I am on music heaven, I really don’t think audio reproduction can get much better. It feels like I am in the high end. My headphones respond very well to eq. Still, if in the future I’ll find myself wanting more punch I’ll consider this, thank you

 

[Jimster480]

@Jimster480 thank you, I equalized my headphones and now feel like I am on music heaven, I really don’t think audio reproduction can get much better. It feels like I am in the high end. My headphones respond very well to eq. Still, if in the future I’ll find myself wanting more punch I’ll consider this, thank you

Glad you were able to arrive at the sound you like through EQ! Enjoy the music!

 

[Aud99]

Just unboxed the unit.

I’m wondering if there’s any way to keep the display showing the VU meter when the unit sits idle?

When I don’t press any buttons for a while, the screen turns black and just shows “SE”.

 

[Dunring]

Just unboxed the unit.

I’m wondering if there’s any way to keep the display showing the VU meter when the unit sits idle?

When I don’t press any buttons for a while, the screen turns black and just shows “SE”.

Yep there's a timeout setting in the menu to keep it on, or let it go screensaver after a set amount of minutes. Screen burn takes years, but it's something to think about. I've had a couple of them and another coming in Friday. It's literally the biggest menu system for an amplifier I've seen, but the setting for screen is in there. At least firmware updates are bulletproof compared to people accidentally flashing the wrong firmware and bricking stuff. Not sure they can take headphone amplifiers anywhere from there, short of a true low gain mode which would be nice for IEMs.

 

[ssn22]

You should test the power vs. frequency graph
Only test the power at 1k frequency
emmmmm
Something to say
The reference value is very limited.

 

[ajax247]

Alas, my A70 Pro suddenly started clicking -- really sounded like it was switching input source for a small fraction of a second -- every 5 seconds or so. That was in PRE output mode. Switching to HPA or HPA+PRE modes made the problem go away for a few days. I emailed Apos and Topping, and Topping suggested I try updating the firmware. I tried that using a Mac laptop -- the A70 display screen showed FW V1.1 was installed, but the disc did not mount. I tried again with a different Mac and a PC, neither of them even got the screen to show, and the disc did not mount. Powering up the unit again, it suddenly froze up with "HPA DC Abnormal" on the screen. Disconnecting and reconnecting, same thing. So, Apos will be sending me a return ticket...

I've had the A70 since May 2023, and it has been great. I'm not looking to change, provided I can get this now defective unit repaired or replaced. Hopefully that won't take too long, but Apos does say they are understaffed...

I'll update when it is all resolved.

Topping took a couple weeks, but did ask me to return my defective A70 Pro, and followed up promptly by sending me a refurbished unit.

So happy to have it back! Audio bliss...

Hope it lasts!

 

[Imaraptor]

But audio drops with my Sundara occurs only to me? I'm a lucky man

Nope! I made an account just to post here because I've been so frustrated with this amp! I've bought two from Apos (bought the second because I didn't want to wait for the RMA from the first) and both units cut out when connected via a computer. I don't understand I've tried so many different DACs, sources, headphones, etc. I did notice that it consistently cuts out at the same parts of specific songs with alot of low end, and that the first amp did, but the second amp's sound doesnt cut out when using my phone as a source. I finally reached out to topping because I figured the odds of two amps doing this, is slim so it must be me. Nope, they ended up telling me to basically "switch songs or return the amp" which is crazy to me because I have a portable DAC/amp (FiiO Q11) that can drive my headphones louder and without having to carefully select the "right" music. What kind of $500 amp only plays certain music, but is supposed to be able to deliver 17 watts per channel?

They stated that this was because of the DC protection. I did send an email asking if they can somehow ship me a firmware that cancels this DC protection and allow me to sign a waiver in the event my amp/myself blows up. Still waiting on a response.
I absolutely love the sound and features/aesthetics of the amp and want to be able to enjoy it with my gf, or I'd try something different. super frustrating either way.
P. S. My amps haven't made a clicking noise, but instead the FFT falls completely and the sound cuts out with a small pop in my headphones. Turning it down substantially to almost quiet listening levels helps, but then what is the point of the amp?

 

[Imaraptor]

Also want to clarify, I am on the most up to date firmware and was on both amps. I don't have voltage tester things, and wouldn't know where to really begin. However, the amos cuts out at the same parts of specific songs even if no headphones are connected.

Thanks for anyone's help!