Headphoneus Supremus
A modern, compact, reasonably priced flagship
Pros: Tons of power
Minuscule output impedance
Two gain modes
Currently the best measuring high power headphone amp ever made
Also a top notch preamp
Features my preferred method of volume control - relay switched R2R in 0.5 dB steps, around 200 steps
Converts SE to balanced and vice versa
Lots of connectivity, especially with the Ext90 extension for inputs
Advanced functionality such as memorizing different volume levels for different inputs, safe volume feature, etc
Remote control included
Compact size, especially compared to old school powerful amps
Amazing price for what it offers
Cons: Not the most power into high impedance headphones, but should be plenty for most (it's good for around 1W into 300 ohm)
No very low gain mode, the lowest is 6 dB
Even with the Ext90, you can't have more than one set of SE and balanced outputs
The humble Topping A70 Pro does it all. Following amplifier design breakthroughs in the late 2010s via nested feedback/composite amplifiers, Topping has adopted this technology to produce amps that provide not only the best technical performance, but they do so at low prices and while being compact. What we're seeing here is the typical evolution of electronics: improved performance, efficiency, smaller size, and lower price. No more need to spend thousands on the best headphone amp, which is hard to believe for some.

So it was time for me to upgrade and try some new equipment. The A70 Pro is really their flagship headphone amp, despite the presence of an A90 and A90 Discrete which are older.


The A70 Pro is packaged like other recent Topping products. It features a display which is a recent design update for Topping models. This is a nice improvement for me, as I'm used to having old school gear without any digital features like this.


The display has multiple modes, including a cute little VU meter which actually has an adjustable scale.


The A70 Pro features one set of SE inputs, one set of balanced inputs, one set of SE outputs, and one set of balanced outputs. It also has their ground loop lifting switch, a USB-C cable to connect to a computer (as a storage device) for easy firmware upgrades, and 12v trigger capability. Mine already came with the latest 2.02 firmware. For headphone outputs you get a 6.35mm SE, 4.4mm balanced, and XLR balanced. You can enable/disable each input/output individually, or have them all active. You can also disable the headphone outs and just use it as a preamp, or vice versa. The functionality of this device is great.


With the A70 Pro, Topping is sort of competing with themselves again. It costs less than the A90 and A90 Discrete and outperforms them, most of all in power output - the A70 Pro is the more powerful amp. It also has a newer interface than them. It also costs less than their Pre90 preamp which has minimal benefits: lower output impedance (20 vs 50 ohm SE and 40 vs 100 ohm balanced) and better crosstalk spec, but neither difference is huge on paper. The Pre90 has around 32 more steps of volume control which is honestly irrelevant, but the A70 Pro has two explicit gain settings unlike the Pre90 which has no explicit gain control.

Curiously enough, the $350 Topping L70 preamp has lower output impedance than the A70 Pro's preamp which is an improvement, granted it shouldn't make any difference realistically as both are low. In any case, the A70 Pro makes it impossible to recommend the Pre90.

As a headphone amp, I tested the A70 Pro with my SMSL SU-X DAC feeding it a 5.2v balanced signal, and the Dan Clark Audio E3 headphones in balanced mode. Although the E3 is rated at 90 dB/mW, low gain is the best option for this matchup, as low gain is still 6 dB. High gain is only for the very low sensitivity headphones of the world such as the HiFiMan HE-6, SUSVARA, and Mod House Tungsten. Note that there's no very low gain mode of 0 dB let alone negative values, so the A70 Pro is not ideal for very sensitive, low impedance headphones like IEMs.

With the AKG K371 or ETA Mini Closed in SE mode, I barely raise the volume in this stack. A lower gain mode would be ideal for them, but with such headphones you just don't need an amplifier of this caliber.


This amp is dead silent, and has tons of headroom with the E3 even on low gain. I did some blind testing comparisons between the A70 Pro and HeadAmp GS-X Mini. One huge, obvious advantage manifested when trying to level match them before the testing. I made the mistake of ordering the GS-X mini with the 24-step DACT stepped attenuator. I like the guarantee of perfect channel matching, since there's a luck of the draw factor here with potentiometers, but never order a measly 24-step attenuator. I can't get my ideal volume out of the GS-X Mini + E3 without resorting to small digital volume adjustments.

So for the blind tests, I just listened at a slightly lower level than I'm used to, and then did another shorter round of blind testing at a higher level than I'm used to, as uncomfortable as this was since with just 24 steps, each step is huge. Compared to the lovely ~200 0.5 dB steps of the A70 Pro, which likewise grants perfect channel matching since it's a relay switched R2R design that works with the remote control. This type of volume control is a requirement for me.

In either blind test, the A70 Pro and GS-X Mini sounded indistinguishable after many rounds on separate days.

I can't really ask for anything else from the A70 Pro, but I also don't have a Mod House Tungsten to test with it. In any case, I haven't encountered any issues with the A70 Pro.

As a preamp and ultra powerful headphone amp, you get the greatest performance in the industry at this power level, for a mid tier price in a fairly compact package, thanks to recent advancements in amplifier design. Now is a good time to let go of old school, huge, expensive audio electronics, as price/performance keeps increasing with these new products.
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Current firmware is 2.02 {IIRC} and it's worth taking the minimal time it takes to update .
^ Also I'll note that mine came with the latest firmware since I bought it recently.
For anyone who cares, I purchased a unit a few months ago that came with firmware 1.01. The direct upgrade to v2.02 went flawlessly and it fixed the vu meter which now works in 10dbu mode.