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Topping A70 Pro HP & Preamp Review

Rate this preamplifier and headphone amp:

  • 1. Poor (headless panther)

    Votes: 15 4.4%
  • 2. Not terrible (postman panther)

    Votes: 7 2.0%
  • 3. Fine (happy panther)

    Votes: 38 11.1%
  • 4. Great (golfing panther)

    Votes: 283 82.5%

  • Total voters
    343

amirm

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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.
Topping A70 Pro Headphone Amplifier Balanced Preamplifier Review.jpg

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:

Topping A70 Pro Headphone Amplifier Balanced Preamplifier back panel remote Review.jpg

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:
Topping A70 Pro Headphone Amplifier Balanced Preamplifier XLR Measurement.png


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:
Topping A70 Pro Headphone Amplifier Balanced Preamplifier RCA Measurement.png


Balanced mode does provide more output though:
Topping A70 Pro Headphone Amplifier Balanced Preamplifier SINAD vs Measured Level Measurement.png


Finally here is our SNR:
Topping A70 Pro Headphone Amplifier Balanced Preamplifier SNR Measurement.png


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:

Topping A70 Pro Headphone Amplifier Balanced Measurement.png

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:
Topping A70 Pro Headphone Amplifier Balanced RCA In Measurement.png


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:
Best headphone amplifier review 2023.png


Noise performance shows why XLR input is a bit better:
Topping A70 Pro Headphone Amplifier Balanced SNR Measurement.png


50 mv output mode delivers near top of the class performance:
Lowes noise headphone amplifier review.png


Frequency response is exceptionally flat:
Topping A70 Pro Headphone Amplifier Balanced frequency response Measurement.png


Multitone performance is superb:
Topping A70 Pro Headphone Amplifier Balanced Multitone Measurement.png


Power is just about everything in headphone amplifiers so let's see how we do there:
Topping A70 Pro Headphone Amplifier Balanced THD 300 Measurement.png

Topping A70 Pro Headphone Amplifier Balanced THD 32 Measurement.png


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:
Topping A70 Pro Headphone Amplifier Balanced power vs impedance Measurement.png


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:
Topping A70 Pro Headphone Amplifier Balanced Channel Balance Measurement.png


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!

------------
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/
 

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Jasperous

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Good lord this thing is beautiful! I await a replacement to the A90D… maybe even powering some small speakers?
 

Doodski

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@amirm under your quote, "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:"
There is a identical image as the one above. So 2 images of the same test shown consecutively.
 

Jasperous

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I just bought my A90 D to replace my A90 because of the remote control… should have just waited out for this beast!!
 
OP
amirm

amirm

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@amirm under your quote, "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:"
There is a identical image as the one above. So 2 images of the same test shown consecutively.
Oops. In bed already. Will fix later. Sinad dropped to 118 and change.
 

Matias

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Stunning performance, simply the best!
 
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How hot does it get over time (1/2 hour)? Thanks for the measurements @amirm now just waiting for a pcb "shot list" and/or photo hoping to see thermal management implementation. This is an end of game headphone amplifier.
 

nicholasvanorton

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Is it better than GUSTARD DAC-X16?
 

Jimster480

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Extremely nice Amp here. As I mentioned in the D70 Review I think that the new design is a little less "clean" with a complex display and such. However the new features are welcome.
Performance is amazing and overkill... honestly I am not sure what headphone needs this much power? I guess it won't matter though since this amp will power any headphone without an issue!

The other question is with so much functionality; will this affect the lifespan?
 
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