Aune S17 Pro is a Beast of a Headphone Amplifier

Aune is not one of those brands that generate hype with every new model, but using and testing the S17 pro I can’t stop and think if that’s going to change. Yes, this headphone amplifier is good enough to generate some well-deserved hype and worry the competition in this price range.

Build and Features

Aune S17 Pro is one of those big and sturdy things. Heavy and completely made of aluminium, it could be used as a cold weapon. The front of the unit is dominated by the big LCD display in the center and the volume knob on the right. On the left side, we find three different headphone output jacks, one of which is single-ended 6.3mm, while the other two are balanced ones in the form of 4.4mm and XLR. The back side is straightforward with two pairs of analog inputs – RCA and XLR, and two pairs of analog outputs of the same variety. These outputs are variable in level, meaning that they are affected by the volume control. Thanks to high input impedance, and low output impedance, the S17 pro can act as a simple preamplifier too.

Aune made a very powerful amplifier that is capable of delivering up to 7.5 W into 32 Ohms over its balanced output. There are two gains to choose from, but more interestingly, there are two different bias currents to choose from – 50 mA and 100 mA. These modes are clearly indicated on the display with the 50 mA one being accompanied by the blue accent color, while the higher 100 mA mode has red joined to it as you can see in the image above. This color scheme is not by accident since higher bias means more current is flowing through the output stage at all times, which results in the amplifier running hotter. Temperature will be shown on the bottom right corner of the screen. I ran this hotter mode for four to five hours straight and maxed at 68 C. This was hot enough for you to clearly feel the heat radiating from the unit, and its metal shell became very hot to the touch. That said, I never got to the point where the amplifier needed to shut down due to overheating but I was testing in a comfortable room temperature of 24 to 25 C. If we’re talking about hotter rooms, or simply very congested space for the unit – which would hamper its cooling – you might hit the safe limit after a few hours, which would trigger a safety shutdown and force you to switch back to the 50 mA mode.

Sound (50 mA mode)

Aune S17 Pro is a powerhouse and it didn’t care about the type or impedance of headphones I was using. It sounded really good and showed great drive with all of them. Dynamics, kick, and slam are always excelling which brings true energy to the music. But if you think that this is some brute that doesn’t deal well with fine details and more subtle music, you’d be wrong. This amp is a true all-rounder performer that is equally happy rocking as it is playing some fine old jazz recordings. For the latter, a big and airy soundstage is quite helpful, and so is the capability of S17 to retrieve a very respectful amount of tone timbre and tone texture. To put it simply, we have a very clean, very dynamic and punchy, tonally neutral, yet decently refined sounding amplifier – what’s not to like?

Sound (100 mA mode)

Switching to the 100 mA mode, the sound signature changes. The extent of the change is not huge but definitely noticeable for a keen ear. The first thing that I noticed was a warmer sound signature, with a rounder bassline and midbass. Midrange changes two, it becomes softer and more refined with tone textures being more obvious. At the same time, tone edges become softer too. No loss of details is happening here, but listeners used to that modern edge-clean performance might miss a bit of that crisp focus. I know I did in a few songs with acoustic guitar strings being plucked. However, in most songs and most music genres, I did lean more towards the 100 mA mode and its lusher, warmer, and tonally richer presentation, with the addition of a slightly bigger and airer soundstage too.

Whether you lean towards one or the other current bias mode, the truth is that both sound great. Switching between the two is so quick and easy that you can really do it on a song basis if you like.

Comparison

Topping A90D is the flagship headphone amplifier from Topping and the one that was highly praised by many, myself included. Looking at features and functions, they’re very similar so I won’t spend time talking about it here. You can always open their spec sheets and see if there’s anything that matters to you specifically. Topping A90D is also a powerhouse, very clean, revealing, and tonally neutral. In a direct comparison, there is not much difference between the flagship Topping and the S17 Pro in its 50 mA mode. They definitely sound more alike than they are different. But take some time to listen critically and you should notice that Aune is capable of even stronger dynamic swings, with ever so slightly cleaner and less cluttered soundstage. It’s not easy to hear at first, but once you spot it, it will be hard to miss going back and forth.

Continuing comparison but with 100 mA mode engaged, the Aune S17 pro starts sounding fuller, more three-dimensional, and more revealing of inner tone detailing. It manages to sound more revealing, yet softer and more natural at the same time. If you prefer this mode on the Aune amplifier, you will for sure prefer the Aune to Topping – I know I did.

Conclusion

Aune has a winner on their hand with S17 Pro if you ask me. They managed to check all of the sonic boxes for most audiophiles to enjoy it thoroughly, in one mode or the other, or both depending on the music and your current mood. Great sonics, great power, a great build, and the right price – what’s not to like? Maybe the sheer size and how hot it runs in one of its modes? I’m aware that might deter some, but if you’re not bothered by that, the Aune S17 Pro comes very highly recommended. Best headphone amplifier I’ve personally tested and reviewed here on the iiWi reviews.

AUNE S17 PRO – CHARACTERISTICS

Inputs: 1x Stereo RCA input 1x Balanced stereo XLR input Outputs: 1x 6.35mm jack headphone output 1x Balanced 4.4mm jack headphone output 1x XLR 4-pin balanced headphone output 1x RCA line output 1x XLR line output INPUT/OUTPUT IMPEDANCE RCA input impedance 10KΩ RCA output impedance 200Ω XLR input impedance 22KΩ XLR output impedance 100Ω Headphone output impedance 1Ω 6.35MM JACK HEADPHONE OUTPUT Frequency response 20Hz – 80kHz (+/- 5dB) THD+N < 0.00038% @1kHz SNR > 115dB @600Ω Crosstalk < -105dB @1kHz 600Ω BALANCED XLR HEADPHONE OUTPUT Frequency response 20Hz – 80kHz (+/- 5dB) THD+N < 0.00016% @1kHz SNR > 116dB @600Ω Crosstalk < -110dB @1kHz 600Ω GAIN-RELATED OUTPUT POWER G-L 6.35mm jack headphone output (Low Gain) 738mW @ 32Ω 250mW @ 100Ω 166mW @ 150Ω 100mW @ 250Ω 83mW @ 300Ω 53mW @ 470Ω 41mW @ 600Ω G-L Balanced headphone output (Low Gain) 2773mW @ 32Ω 968mW @ 100Ω 645mW @ 150Ω 388mW @ 250Ω 333mW @ 300Ω 212mW @ 470Ω 166mW @ 600Ω G-H 6.35mm jack headphone output (High Gain) 2020mW @ 32Ω 675mW @ 100Ω 453mW @ 150Ω 273mW @ 250Ω 228mW @ 300Ω 145mW @ 470Ω 114mW @ 600Ω G-H Balanced headphone output (High Gain) 7507mW @ 32Ω 2643mW @ 100Ω 1793mW @ 150Ω 1089mW @ 250Ω 908mW @ 300Ω 580mW @ 470Ω 453mW @ 600Ω GENERAL Dimensions 211 x 288 x 63mm Official product page