Aune X7s Balanced Headphone Amplifier REVIEW

Sometimes, simple is better. This can be particularly true when it comes to audio equipment. Take, for example, the Aune X7s headphone amplifier. It’s designed to do one thing, and one thing only. That level of focus makes it easy for the design team to make it do that one thing well.

This isn’t to say that audio equipment with loads of functionality is all bad. Of course not. There are some superb products out there with high levels of versatility. Take Klipsch’s brilliant The Fives powered speaker system, or one of my favourite pieces of hi-fi gear ever, Rotel’s amazing RA-11 integrated amplifier – reviewed in 2013, but so good I still remember it fondly today. Both are Jacks of all Trades, and Masters of those trades too.

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In a world where it’s entirely possible to buy a product that combines digital to analogue conversion with Bluetooth streaming, and headphone amplification, and probably a coffee maker too, the X7s really has to be good purely as a headphone amplifier.

Construction and features

The X7s is a compact but chunky unit, measuring barely bigger than a standard CD case, albeit far taller. Build quality is good. The thick front plate and the body’s curves make for a structure that’s not going to be subject to much in the way of resonance or vibration. The X7s feels remarkably solid, despite not weighing as much as anticipated. The reason for the relatively light weight is the external power supply, which is a chunky, well-regulated unit with captive cables. This is a plus in some ways because it removes any audiophile temptation to start fiddling around with aftermarket power cables.

Controls are limited to the smooth-moving volume knob around the front and a power switch round back. Hidden underneath are the dip switches that adjust the gain. Inputs are limited to the power socket and two RCA analogue inputs along with two RCA outputs. The X7s offers both XLR balanced and standard 6.35mm headphone jacks.

The X7s is a Class A design, which has been specifically tuned and tested with a number of high-end headphones, according to Aune’s website. Power output from the standard jack is listed as 250 mW into 300 Ohms and 1000 mW into 32 Ohms, with the balanced output delivering a substantial 1000 mW into 300 Ohms and 1700 mW into 32 Ohms.

Listening

The X7s immediately displayed one of the most attractive features of any headphone amplifier – the “Is this thing on?” factor.

When you turn on many pieces of audio equipment, there’s a clear impression that they are in fact, on. A buzz, a hum, a barely palpable sense of electricity flowing. Be it ever so subtle, some noise or sensation tells you the circuits are now active. Not the X7s. This thing is as dead as a chunk of ancient stone on a hillside until you push the play button on the CD player, when it comes to vivid and energetic life.

Keeping things simple, I plugged the X7s into my old Marantz CD6000OSE CD player. I’ve had this unit since 2006, and when I bought it, it was by no means new. But it’s been one of the best ways to spend $200 because it’s still going strong and most importantly, still sounds bloody fantastic considering it was never a high-end player. Ken Ishiwata got lots right with the Original Special Edition components back in the day. The X7s takes that heritage and runs with it.

With a set of Monster 300 interconnects in the loop, my old Sennheiser HD650 headphones connected, and Van Morrison’s ‘Rough God Goes Riding’ from The Healing Game playing, I was immediately captivated.

I’ve loved this album (well, almost all of it) since I first heard it about 14 years ago. Several adjectives came to mind when I contemplated the sound from the X7s – smooth, rich, open, effortless, and fast were just some of them. But based on hours of subsequent listening, I learned that’s what the X7s does to music – it adds the best kind of adjectives.

‘Rough God Goes Riding’ is filled with small details that are easily obscured by lesser systems. The harmony vocals and the low-level sound of the brass on the drum kit for example. But there’s also that closely-miked main vocal, the drums, and of course, the horns, which dominate parts of the track. Play the horn solo which starts at 2:23 loud, and it can sound strident, even harsh on some systems (which is why this song is still on my review list after all these years). It’s all too easy to want to reach for the volume knob to get some relief, but that was the last thing on my mind. Instead, I added a few degrees of extra rotation in the loud direction to get immersed further into the song. At no stage – no, not even once – was a break needed. Best of all, all the subtleties of the recording were still there in abundance.

Another track that can be difficult on the wrong system is ‘Siva’ from Rotten Apples, The Smashing Pumpkins’ Greatest Hits. At high volume, the short burst of drums at 1:08 sounded fantastic. Powerful, intense, and dramatic. And if you can survive the guitar that kicks in at 2:20, or the craziness that starts at 3:43 at exceptionally high volume without cringing or leaping for the volume control, then perhaps you’re listening to a tranquil system that’s making everything safe for baby’s little ears. Or you’re listening to something that can give you everything on the recording but not make it sound harsh while doing so. The X7s is that something.

Admittedly, the HD650s lean slightly to the equation’s warm side, but the X7s was a perfect match, adding zero warmth but still keeping things smooth. There was huge impact from the drums, but the vocals and guitars never veered into being too much, let alone shrill or fatiguing. This is one of those “listen all day” kind of pairings.

One more track on this album that’s a must-hear with the X7s is ‘Stand Inside Your Love’. This track was cranked up to levels I seldom approach because I’m genuinely fearful of hearing loss but damn, what a performance. The song is all about power and energy, and once again, it can be cringe-inducing with the wrong gear. For example, the part that launches like a Saturn rocket from 0:58 is superb with the X7s/HD650 pairing, but it’s awful with a set of cheap metal dome tweeters or budget earphones as I’ve found to my cost in the past.

The treble extension and quality on the X7s are beyond reproach. As clear as glass with none of the fragility, it’s one of the sheer joys you get from a well-engineered Class A headphone amp. It sounds like music, pure and simple, organic, natural, and enjoyable. That’s why hi-fi and head-fi can be so special.

So, that’s almost a rapturous initial reception to the X7s. And that was all achieved using my backup CD player and some basic interconnects. The next step was getting my treasured Marantz SA8260 into the fun, along with some better bits of cable. The Marantz has been with me for a long time. Like most of my audio gear, it’s stuck around for the simple reason that I can’t find anything that does the job better for less than silly money.

With one of Nordost’s Wyrewizard Magus power cables powering the SA8260 and a half meter set of the wonderful NZ-made Slinkylinks silver interconnects (cryo-treated if we’re precise), it was back to The Smashing Pumpkins for a second listen of ‘Stand Inside Your Love’.

Cue up more of everything, from deeper, more powerful bass to an extension of the treble clarity and energy, and a more open midrange. In short, a more transparent window into the recording as additional layers of information was retrieved. The SA8260 isn’t quite as smooth as the CD6000OSE, but its talent stack is much broader, especially in terms of dynamics and absolute detail retrieval.

At relentlessly, perhaps even foolishly high volumes, the sense of pure audio fidelity was strong as I focused right into the recording. Do you want to hear your music? As in really hear it? It’s hard to beat headphones because they will get you closer to the music. And good headphones with a high-quality source and a stellar amp like the X7s do things it takes a lot of money to replicate in a hi-fi system. Whatever component could stand to be upgraded in this particular “on the fly” system, it wasn’t the X7s.

At this juncture, with ears ringing, I had to move to a more relaxing type of music – beautifully recorded, preferably by someone gorgeous – something mellow and easy to listen to at low levels, and with some audiophile credibility too. Just A Little Lovin‘ by Shelby Lynne seemed perfect for the task. What a pleasure this turned out to be! The X7s put me front and centre for a personal and intimate performance of the title track. The two words that describe the sound are smooth and detailed. When it sounds like you’re standing a couple of meters from the microphone, and you can hear the way the artist shapes every word, and how she moves the air between words, well, then you’re most definitely in the land of high-fidelity.

The treble quality is something I noted once again. There’s nothing artificial or contrived about the way the X7s play back the high frequencies. The noise floor is imperceptible, making the treble sound even silkier and more highly-resolved. There are zero issues with the midrange or the lower octaves either. Bass notes have a weight and precision that speaks of the headphone diaphragms being controlled by a well-designed, powerful, and capable amplifier. The way notes start and stop reinforces this sense of authority. The HD650s have a reputation for being a little challenging to drive, and rewarding clean power. But with the right amplification, like an X7s, they can absolutely sing.

Without a high-resolution DAC on hand, the next best thing was to run a series of well-recorded SACD discs through the Marantz to try to find any weaknesses in the X7s. Diana Krall’s The Girl In The Other Room has been one of my go-to test albums for a long time, and for a good reason. It is a beautiful recording, and much like the aforementioned Shelby Lynn album, the X7s had no problem making it sound as good as it should. The instrument separation was excellent, and the sheer quality of the piano and vocals on ‘Narrow Daylight’ had a warmth and depth of detail that made me think I was listening to a more expensive amplifier.

In addition to the HD650s and my set of Sennheiser Momentum headphones, the X7s was tested with three different in-ear monitors, mostly to see if it proved to be a mismatch with any of them, but also to see if the noise floor was as low as it seemed. All I got from this experiment was a sense that the X7s can pretty much do no wrong, and that yes, the noise floor is indeed, exceptionally low.

Conclusion

Which brings us back to the start of this review. The X7s manages to do the one thing it’s designed to do very well indeed.

It combines excellent build quality with a refined, immersive, and neutral sound that offers just the right amount of richness and smoothness. The music always comes from a dark, ultra-quiet place thanks to that impeccable noise floor. It does all this while still staying mostly true to the information being fed to it by the source. It’s a paragon of both subtlety and dynamic musical power. At the price, it’s almost a no-brainer, especially considering the fact that it also supports ‘phones with balanced cables.

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