In this review, I’m taking a look at Aune’s flagship solid-state headphone amp, the Aune S17 Pro EVO. It’s selling for $799 USD.
Disclaimer: Aune is not related to Headfonia. They sent me the Aune S17 Pro EVO to be featured on Headfonia.com.
Aune
Aune or “Wuhan Aune Acoustics Co. Ltd.” was launched in 2004, so in many ways, they’re a veteran in the personal audio space. In their own words, Aune are diehard music lovers and audio fans as well as experts in making hifi products. The latter is a bit of an understatement because they have a lot of products on offer for both personal and even car audio.
Nowadays, Aune are known for offering a full chain of audio electronics in the S-series. Their S10N and S10 Pro network audio players, with the latter adding an ES9038 Pro DAC in the mix. The SC1 Evo is a dedicated 10MHz master clock, and the S9c Pro is a combo DAC/amplifier.
Lately, Aune have also caused quite the buzz with the AR5000 and SR7000 full-size dynamic headphones. With the former being closed-back and the latter open-back. In the not-so-distant future, Aune also promise to release a flagship open-back AR9000 and interesting clip-on portable headphones similar to Koss’s offerings.
Aune S17 Pro EVO
As is denoted by the “EVO”, this is the second iteration of the S17 Pro amplifier design. The fundamentals are still there – it’s a solid-state Class-A headphone amplifier and preamp with true differential circuitry. From the outside, the only thing that’s changed is the addition of the “EVO” badge.
Whilst there are some quality-of-life improvements like separate volume settings for the preamp and the headphone amp, there’s one issue Aune went all-in to tackle. You see – the S17 Pro is a Class-A amp, so it runs at full power all the time. So, it runs hot. Do you see any heatsinks or vents? Ah, now you get it. The original S17 Pro was quite prone to overheating.
The EVO edition adds a smart feature that constantly monitors the temperature of the amp and when it gets dangerously toasty at +69C (nice!), the circuit switches to a lower quiescent current. Does that mean the S17 Pro EVO suddenly leaves Class A? Nope, it’ll still be in that magic region unless you drive it extremely hard.
You can get the Aune S17 Pro EVO for €839 EUR or $799 USD at their official store, Amazon US and at other retailers.
Features
- Amp type – discrete solid-state, high-bias, push-pull, JFET-input, BJT-output
- Coupling – capacitor-coupled input
- Volume control: chip-based stepped attenuator
- Inputs: RCA and XLR (switchable)
- Outputs: 4-pin XLR, 6.35mm TRS, 4.4mm TRRRS, RCA, and XLR
- SNR: 115dB (worst case)
- THD+N (@1kHz): <0.0003% SE, <0.00016% (inaudible)
- Gain: +8.9dB, +13.6dB
- Output power: max 7.5W@32ohms, max 459mW@600ohms
- Output impedance: 1ohm HP-outs, 200ohm RCA, 100ohm XLR.
- Power draw: around 50W
- Dimensions: 211x288x63mm
- Weight: 3kg
Design, Build & Haptics
The outside architecture of the Aune S17 Pro EVO is almost identical to its predecessor. The amp isn’t small and doesn’t follow any size standard, so stacking it on top of some DAC will be tricky. Looking to stack something on top of it isn’t hard due to its arched top; the main challenge will be thermals.
On the front panel, we get the usual set of headphone outputs in 4-pin XLR, 6.35mm TRS, and 4.4mm TRRRS. For the volume control, we use a pretty chunky knob that drives a nicely dampened encoder. The middle is dominated by an LCD screen, which shows most of what you need to know about the S17 Pro EVO’s current operating status. There’s also a small IR receiver and a pinhole for the red status LED.
The back is more straightforward – we get SE and BAL inputs and outputs for preamplifier duty. The only way to turn the amp on is to reach back and flip the rocker on the IEC input panel. I guess Schiit Audio’s legacy lives on in other companies’ products as well.
To control the S17 Pro EVO over a distance, we get a neat-looking remote. It allows for changing the volume, gain, high, and low bias as well as toggling between XLR and RCA inputs. What’s missing is the on/off button and switching between the headamp and preamp modes.
I wasn’t entirely happy with the LCD screen. It uses a TFT-matrix display, so the colors get inverted even if you’re slightly off-axis. Making out the volume setting is quite effortless, but everything else from further than desktop distances won’t be visible. Of course, living room duty will be more hampered by the need to reach behind the chassis to turn the amp on.
In use
Living together with the Aune S17 Pro EVO is quite effortless. Once you’re used to the turn-on ritual, the rest is quite easy. The amp is ready to roll after a couple of seconds when the protection relays engage. If you look at the screen right after you turn it on, you’ll even see your current room temperature!
After the S17 Pro EVO has been turned on, you’ll see that the temperature number will rise steadily. I wasn’t able to detect any correlation between driving the amp hard or using preamp mode and how hot it was, which means the circuit was in Class-A all the time. Aune claim that low-bias is 50mA and high-bias is twice that, at 100mA. This also tells me that in higher power output, the S17 Pro EVO can leave Class A, but good luck hearing it.
In high bias, the S17 Pro EVO runs quite toasty at over +60C. At regular room temperatures, it never had to change gears to low-bias, but I can see it happening if your room is over +25C or if there’s not enough airflow around the enclosure. It’s obvious that the output stage is thermally coupled to the chassis, and the top acts as a huge heatsink.
The volume control uses a JRC chip with on-silicon resistors and switches. It’s a nice solution because the tracking accuracy doesn’t deteriorate at lower volume settings. All of the switching is done by solid-state relays, so there’s no clicking. It’s likely that the decision to use coupling capacitors at the input was also made to mitigate switching noise when changing volume.
Stepped attenuators are quite sensitive to DC and make a purring sound when volume steps are changing.
The Aune S17 Pro EVO article continues on the second page. Click on the jumps below to go there.
