Topping A70 Pro HP & Preamp Review

[Am1n985]

I don't think you'll have any luck with either headphone amplifier.

According the Specs the Aune S17 Pro Evo delivers 7,5W at 32 Ohm.
View attachment 462627
According to @amirm's measurements, the A70 delivers 8.22 W into 32 ohms.
Therefore, I expect the same inadequate results from the significantly more expensive Aune S17 pro.

The S9C Pro only has a power output of less than 5.5 W at 32 ohms. Therefore, it will reach its limits even faster.
View attachment 462628

I therefore recommend buying a power amplifier for your insensitive headphones, as most headphone amplifiers deliver less power at 32 ohms than the A70.

An excellent choice may bet the Topping B100 amplifier. He delivers 100W at 4Ohm which means 12.5W at 32Ohm. This will probably be sufficient. You need an adapter from Banana to XLR or 4,4mm TRS and you're done. Cheap solution and power without end...

If this still isn't enough get a NCx500. It will deliver 500W at 4Ohm which means 62,5W at 32Ohm.

Best DrCWO

Thank you very much for the suggestion.

To keep costs down rather than buying 2x B100 (they do look fantastic and extremely low distortion), I'll be running a Topping E70 DAC with this setup, how would a Topping PA7 or PA5 II fair instead?

Which specs in particular of these amps am I most interested in to ensure these power amps are ‘suitable’ for headphones.

The planars I’m struggling with are 11-ohm.

 

[staticV3]

Which specs in particular of these amps am I most interested in to ensure these power amps are ‘suitable’ for headphones.

Frequency response at various load impedances to make sure there's no egregious treble resonance

SNR/absolute noise measurements to make sure the headphones won't hiss

Everything else is secondary IMO

 

[DrCWO]

Frequency response at various load impedances to make sure there's no egregious treble resonance

SNR/absolute noise measurements to make sure the headphones won't hiss

Very good arguments.
I would still choose either a NCX500 (as proposed above) with extremely low noise and a stable frequency response regarding different speaker impedances.

Both the Topping PA7 and the PA5 have neither a constant frequency response with varying impedance nor an excellent noise performance.

One other choice regarding noise may be the Topping LA90 Discrete. But it offers only 70W at 4Ohm which means 8.5W at 32 Ohm and this seems to be not enough.

Best you get an amplifier with more than 120W at 4Ohm and extremely low noise.

Best DrCWO

 

[Am1n985]

I ended up returning the SJY headphones (other than being a pain to drive, I didn't get on with the comfort).

Did end up getting 2x Topping B100's alongside my E70, connected both via XLR, and got a XLR to 4x banana plug adapter, sounds phenomenal on mid-gain running my HE1000 Stealths. Plenty of headroom even with a -7db pre-amp - so should be covered for any future endeavours.

I won't derail this thread further since it's meant to be A70 Pro focused.

Thanks again!

 

[Steakhouse]

Topping claims that the A70 Pro works down to 8 ohms, but apparently, in Amir's test, it also shut down at 12 ohms and high power.
Perhaps this is something Topping could change with a future firmware update.

View attachment 462090

My suspicion would be that the A70 pro might not be able to put out 15W below 100Hz or so. Amir only tested 12 Ohm with a 1KHz tone and not the full bandwidth. I would not be surprised if the A70 pro would show some irregularities when tested at 12 Ohm with low bass notes. It seems to me rather engineered for this test suite of Amir.

 

[Jimster480]

My suspicion would be that the A70 pro might not be able to put out 15W below 100Hz or so. Amir only tested 12 Ohm with a 1KHz tone and not the full bandwidth. I would not be surprised if the A70 pro would show some irregularities when tested at 12 Ohm with low bass notes. It seems to me rather engineered for this test suite of Amir.

15W? This is a headphone amp lol

 

[olds1959special]

What is the input sensitivity for the Bal input? My Duet 3 puts out almost 7 volts. Will I have to attenuate the volume?

 

[staticV3]

What is the input sensitivity for the Bal input? My Duet 3 puts out almost 7 volts. Will I have to attenuate the volume?

The A70 Pro clips above 9.4Vrms input voltage:

N

Post in thread 'Topping A70 Pro HP & Preamp Review'

May 21, 2024

Simple measurements and pictures of A70 Pro. Bought new on Amazon last week.
https://www.audiosciencereview.com/...g-a70-pro-hp-preamp-review.44636/post-1589231
https://www.audiosciencereview.com/...mark-hpa4-headphone-amp-pre.8141/post-1977315

• nagster

• 

 

[p30better]

What is the input sensitivity for the Bal input? My Duet 3 puts out almost 7 volts. Will I have to attenuate the volume?

The Duet 3 can push almost +19 dBu, which is close to 7 volts. If the gear you’re connecting to can handle +24 dBu, you won’t have any issues. But if its input tops out around +18 dBu, then yeah, you’ll probably need to dial the Duet’s output back a bit or throw an attenuator in the chain.

 

[olds1959special]

I got my A70 Pro headphone amp. I am using HD650's with a balanced cable. I use the balanced outputs of my Apogee Duet 3. I loved the sound in low gain mode, but it's even better in high gain mode. The sound is very smooth and the bass is the best part. I am listening at about -35.0dB right now. I don't know when it might clip, but I'm not hearing that at these levels. I'm rediscovering old recordings with this setup and it's fun!

 

[Thighsofsteel]

I treated myself to one of these bad boys. Its fabulous. I am using it as a pre amp mainly, but with some headphone use when her Ladyship tells me to turn it down. It is in my PC/Office system. Fed by a Fosi ZD3.
I am a happy customer.

 

[olds1959special]

After trying both, I think low gain is better for my HD650's and would have less distortion. I'm really enjoying this headphone amp using my bus-powered Apogee Duet 3 as a balanced DAC.

 

[olds1959special]

I just started using mine as a pre-amp too. I plug my subwoofer into the XLR outputs and my single ended amps into the RCA outputs. I'm now using my Apogee Duet 3 connected through the balanced inputs as a source, and I no longer need my SMSL DL200.

I've been using digital volume controls with all my speaker systems until now!

 

[olds1959special]

I stopped using it as a preamp as direct from dac sounded better.

 

[olds1959special]

What's wrong with using the high gain setting for HD650's? Aren't 300+ ohm headphones what this was made for?

 

[jmdesignz2]

I stopped using it as a preamp as direct from dac sounded better.

Really? I was considering using the new version of the Topping A70 PRO as a preamp. Does yours have the TangKuLa mod?

 

[Earwax]

Really? I was considering using the new version of the Topping A70 PRO as a preamp. Does yours have the TangKuLa mod?

This also sparks interest as I have the L30 II and when using it as a pre amp between the D50 III Dac it definitely adds more to the audio not just db but cleaner / more pure on my AVR 140 amp now in my bedroom....


So I was hoping the A70 Pro would have the same affect from the D50 III Dac to B100 amps.

I`m lacking the education in this arena to comprehend why adding the A70 Pro as a pre amp wouldn't OR would make an improvement at least in my particular set up, from the above experience I`m leaning that it would be an upgrade.

D50 III Dac, B100 amps , Wharfedale Arura 2 speakers.

 

[jmdesignz2]

This also sparks interest as I have the L30 II and when using it as a pre amp between the D50 II Dac it definitely adds more to the audio not just db but cleaner / more pure on my AVR 140 amp now in my bedroom....


So I was hoping the A70 Pro would have the same affect from the D50 II Dac to B100 amps.

I`m lacking the education in this arena to comprehend why adding the A70 Pro as a pre amp wouldn't OR would make an improvement at least in my particular set up, from the above experience I`m leaning that it would be an upgrade.

D50 II Dac, B100 amps , Wharfedale Arura 2 speakers.

If you’re using the DAC as a preamp and it uses a digital volume control then it will make a huge difference if you’re a critical listener to use the Topping A70 Pro as a preamp

Digital volume control truncates in order to reduce volume

Digital volume control works by
multiplying the numerical values in a digital audio stream by a gain factor (less than 1) to reduce their amplitude, thereby lowering the volume. This process, known as attenuation, decreases the numerical data representing the audio signal, and while effective, it can lead to a loss of resolution by truncating the least significant bits.

This can decrease dynamics among other things

 

[Earwax]

I'm getting popping sounds when driving the HE6se at >-10 dB on high gain for testing. Is it normal or is my unit defective?

Check your cables, for me it`s always been the cables RCA / TRS / XLR they all can have defects usually at the ends where wire meets metal.

I also had an issue with these Monoprice 3 foot TRS was pooping like a static I`m sure it was the clear rubber tube protective cover that had the exposed wires chambered in that static inducing environment of the rubber.

I returned the 3 ft and ordered the Monoprice 1.5 foot version TRS no rubber tube but the shrink-wrap was not shrunk on each wire so a quick blast with my heat gun solved that problem and no static.

The blue plastic TRS cables had no shrink wrap or static sounds just pure clean signal no heat gun needed.

Both found on Amazon.

I`ve since made my own TRS and RCA cables with proper results using 18 AWG & 24 AWG along side each other it`s a very tight fit to solder and the housing ends no longer fit but it works.

 

[tonimccloud]

Yesterday I received the A70 Pro. Very nice and compact, though the finish is average at best. My first impressions are that it drives the Abyss 1266 fantastically well. BUT every time I turn it off from the amplifier and then turn it back on, it freezes, and the screen shows “DFU version v2.05.” If I switch it off from the back and then turn it on again, everything works correctly. Is this normal? I think it’s going back to Amazon.

Regards,