Review: Aune X8 XVIII BT and Aune X7s 2021

Even with the basic equipment, the Review: Aune X7s and especially the Aune X8 XVIII BT offer very good or outstanding performance for the money, in terms of equipment as well as sound.

Does it always have to be expensive? Of course not! The price is always decisive, even if it is actually just one of many aspects that should be considered when making a purchase decision. However, it often allows conclusions to be drawn about the other aspects: A small budget often results in low-quality components and housing, run-of-the-mill circuit layouts and a simple design, which dampens the “want to have” factor. can affect. Well, and then the adjustable D/A converter Aune X8 XVIII BT (349 euros) and the headphone amplifier/preamplifier Aune X7s 2021 (299 euros) come around the corner – and just call this statement into question.

Even the high-quality designed boxes obviously want to nip any danger of a Billigheimer image in the bud. They wouldn’t actually need it if you could see and touch the devices directly. Because in terms of design and feel, nothing indicates the very moderate prices. The stackable housings feel valuable, they are chic and designed with a high recognition value. Given the looks, tactile quality, and solid volume knobs of both devices, you wouldn’t think price tags that double or triple the price are unjustified. Let’s look at the two in detail.

D/A converter and preamplifier Aune X8 XVIII BT

Like its headphone amplifier counterpart, the converter preamplifier subtitled “Magic DAC Bluetooth aptX HD LDAC” comes in an aluminum housing with the dimensions of a small cigar box. The satin aluminum housing does not rattle and even reacts surprisingly “dead” to the obligatory knock test, i.e. well damped. The rotary volume control sits on a solid aluminum front, into which small, unobtrusive LEDs for displaying input and digital filters (more on that in a moment) and an on/off pushbutton are precisely embedded. The aesthetics of the front remind me a bit of Technics – not a bad reference.

The X8 XVIII is not the eighteenth version of the X8 model, but the further development of the original Aune X8 “Magic DAC” on the occasion of the 18th anniversary of Aune. In addition to the classic features of the original, such as the interchangeable OP amps (more on that in a moment) and the digital filter modes, the anniversary model also has a balanced TRS preamplifier output with 6.35 millimeter jack plugs (TRS = Tip-Ring-Sleeve) and supports in the present Bluetooth edition – recognizable by the “BT” in the name and the screwable stub antenna on the back – the codecs AAC, aptX HD and even the quite new LDAC.

If you control the Aune X8 XVIII via USB via the PC or the streaming bridge, it supports high-resolution digital signals up to 768 kHz and 32 bits as well as DSD512. At least 384 kHz and 24 bits and DSD as DoP128 (DSD over PCM) via S/PDIF via coaxial input, and the optical input closes the shop at more than 192 kHz and 24 bits or DoP64.

Incidentally, Aune relies on a specially developed and programmed FPGA for conversion and signal processing – a “Field Programmable Gate Array”. This is an integrated circuit (IC) into which a logical circuit (configuration) can be loaded and which enables user-specific circuits, even in small quantities, as well as easy updateability – if you master this kind of thing well, you can not only make yourself independent of supplier parts, but also go completely new, creative paths.

The signal comes out not only via the said TRS sockets, but also unbalanced via two cinch doubles – either volume-controlled for connecting a power amplifier or active loudspeakers, or with a fixed line level for controlling the in-house headphone amplifier, for example.

Special magic

Something quite unique (as far as I know) is Aune’s user-replaceable operational amplifier, which is responsible for amplifying the analog output signal. This feature allows you to personalize the X8 or fine tune the sound with the different distortion characteristics of the op amps to match the rest of the chain.

Always included with the Aune X8 XVIII BT are the pre-assembled NJM5532 operational amplifier and an additional OPA2134. Aune supplies an extra set with the three additional OP amps MUSE01, LME49720 and OPA2604 for around 55 euros, and the German Aune store will soon also be offering the even higher quality (and more expensive) OP amps from Sparkos. The replacement procedure is simple: there is a small cover in the bottom of the Aune X8 that can be unscrewed and gives access to the OP amp. A special pair of pliers supplied makes it possible to safely remove the OP-Amp. When inserting, you just have to pay attention to the correct (well marked) orientation. Voila!


The Aune X8 CVIII Magic DAC offers a whopping seven digital filter modes. Theoretically, there are seven (albeit subtle) different sound gradations available – together with the interchangeable operational amplifiers, there are plenty of opportunities to really let off steam.

Headphone amplifier Aune X7s 2021

The Aune X7s 2021 is already the third generation of the X7s. Compared to the DAC-Pre X8 XVIII BT, its job description is quite simple: It amplifies the signal coming in via RCA jacks with a (according to the manufacturer) puristic Class A design and should also cut a fine figure as a preamplifier. Eight power transistors work in four groups, fine Panasonic SMT film capacitors are used, an ON high-frequency triode and an ALPS audio potentiometer. In addition, strict quality control with the Audio Precision audio analyzer should guarantee that there are no outliers.

There are three DIP switches embedded in the bottom of the Aune X7s, which can be used to select the gain levels of 0 dB, 6 dB and 12 dB. So the headphone amplifier should be maximally compatible with all types of headphones. With the Aune X7s 2021, these can be connected via a headphone output with an unbalanced 6.3 mm jack socket or a balanced four-pin XLR output. The latter is not exactly a matter of course, especially not in this class.

The Aune X7s should deliver more than adequate performance for most applications. The jack output provides 1 watt at 32 ohms and a good 250 milliwatts at 300 ohms. At the XLR output, even fat 1.7 watts are possible at 32 ohms and still 1 watt at 300 ohms. The X7s should deliver the first 200 milliwatts in pure Class A.

PSU upgrade Aune XP2

As a small additional treat, Aune has included an upgrade power supply unit with the XP2 in an elegant aluminum casing (109 euros). The DC linear power supply should have a toroidal transformer adapted to the Aune-X devices and isolate and stabilize the current as well as possible.

It supplies 1.5 amps and 9 volts DC to each of the two DC outputs and replaces the standard switching power supplies found on the X-Devices X8, X1s, X1s Pro, X5s and XC1. The X7s headphone amplifier cannot be connected to the XP2, probably due to its higher energy requirements.

Aune X8 XVIII BT and Aune X7s 2021: listening test and comparisons

First – and with a certain focus – I test the Aune X8 XVIII BT DAC preamp. I feed it with the high-resolution digital USB signals from my streaming bridge Waversa Systems Wstreamer (900 euros) (I use Qobuz via Roon as the streaming service) and in Bluetooth mode with an iPhone 13 – i.e. with the AAC codec. In order to limit the degrees of freedom in view of the “infinite” possibilities, I first listen to it as a DAC preamplifier on my reference system and only later as a pure converter on the Aune X7s headphone amplifier – and basically with the pre-installed NJM5532 op amp. I will say a few more words about the differences with the various other OP amps later.

For the digital filters, I like “fast roll-off, linear phase” (display A) best in the context of the basic sound characteristics of the X8 XVIII – if you like it a little more “romantic”, you will probably choose my second filter favorite “slow roll-off “minimum phase” (display D). On the other hand, it gets a bit harder and brighter with the “Brickwall” filter (display C+D). As already mentioned, the differences are rather subtle, but at least in the long term and subliminally they can make the difference between weal and woe.


The Aune X8 XVIII BT shows no tonal weaknesses, neither with USB signals nor with Bluetooth playback. It doesn’t emphasize any frequency range , only yielding a tiny bit at the end of the frequency response when compared to unfairly more expensive competition. The deepest bass parts, like in Massive Attack’s “Pray for Rain” (album: Heligoland), are not quite as rich and not as contoured from the woofers of the ATC SCM50PSL as with the DAC option of my Norma Audio preamp REVO SC-2, which alone is already at 2,000 euros and thus a multiple of the Aune – even in the super high tone, the Norma, which is soft in itself, delivers a little more energy. Between the extremes, however, I can attest with a clear conscience that the Aune has a fairly straight frequency response – even if the characteristics of the X8 XVIII BT tend to be on the smooth, pleasant, creamy side, also because of its rich tone painting.

Be that as it may, the Aune X8 XVIII BT doesn’t belly or starve the bass on Nenad Vasilic ‘s “Bass Drops” (Album: Bass Room ) – you can visualize the body of the instrument – and he lets the voices of Jacintha, Bruce Springsteen and Tom Waits sound just how they sound and doesn’t darken the brasswork on Jazz at the Pawnshop .

Dynamics, resolution, space

My respect is even greater when we come to the topic of dynamics , because this is where the Aune really comes into its own. It’s fast, damn fast, in every frequency range. And he can implement this speed with a lot of energy in coarse dynamics just as impressively as with small signal amplitudes, vulgo fine dynamics. The stupid but fun “Tsunami” by DVBBS & Bourgeois bangs really hard with tight, powerful bass and a pointed pressure point in the middle. But the Aune is not a dumb bang, as he proves immediately afterwards when Tools drum wizard Danny Carey uses his percussion in thousands of volume levels on the stroke of genius Fear Inoculumcaresses and tickles. The way in which the Aune X8 XVIII BT traces the fluffy tom sequences fluently, loosely and pointedly amazes me at this price.

When we talk about fine dynamics, we also have to talk about resolution. This is one of two disciplines in which the Aune X8 XVIII shows its low three-digit price tag – provided the subsequent chain has the appropriate talents. Because honestly, what I’m telling you here can only be heard on really high-resolution devices. Be that as it may – in any case, the X8 no longer seems to unravel the finest treble webs of the drum cymbals in Max Roach’s “Lonesome Lover” (Album: It’s Time) quite as delicately as the German streaming converter preamp Lindemann Limetree Network II (1,000 euros).

The second discipline is the space – or no: the size of the stage. Said Network II can open up the room a bit higher and wider, and also lets it breathe more dynamically when it matters. The Aune is more compact, seems more intimate, doesn’t want to play on the big stage at all, but prefers the chamber theater. On the other hand – or just because of that? – it actually manages to come almost within striking distance of the Lindemann, which is three times as expensive, when it comes to edge sharpness and three-dimensionality and fascinates immensely with its lifelike, solid projection.

Can my somewhat outdated portable DAC/headphone amp iFi Audio nano iDSD (around 200 euros) keep up? No – he’s actually out in terms of tonality, plays much less neutrally and openly. What about the more modern, volume-controlled streaming DAC Argon Audio Solo (249 euros)? It does better tonally, but comes with comparatively limited coarse and fine dynamics and duller tones not even close to the Aune X8 XVIII. In fact, only the Lindemann stops the dynamic soaring of the compact Aune with even more authority. Admittedly, the latter two devices can be used even more flexibly than the Aune with their wireless streaming capabilities – but that in no way diminishes the sound performance of the X8.

recipe variations

All of the above is to be appreciated with certain reservations, because the interchangeable op amps of the Aune X8 XVIII BT allow quite clear adjustments to personal taste – and more audibly than the digital filters can. I cannot and do not want to tell you which OP amp is “the best” – the dependencies on the device peripherals and taste are just too great for that, and it would go beyond the available framework. For my situation with the overall rather elegantly smooth combination of Norma audio electronics and ATC loudspeakers and with the digital filter A (fast roll-off, linear phase), I tend towards the “brightest” and most analytical OP amp, the LME49720 , which gives impulses an even clearer edge and an extra kick and illuminates the treble a little more. On the other side is the OPA2132, which plays with almost tube-like soft charm. The NJM5532 used ex works should be the optimum for friends of an overall balanced and solid balance and smoother higher frequencies. In any case, this is a great opportunity for fine tuning. Very cool!

New energy: The XP2 power pack

Plug (switching) power supplies are mostly frowned upon among audiophiles. With the XP2, Aune offers a fairly inexpensive solution for a particularly stable power supply for up to two X-Line devices (except for the X7s headphone amplifier).

What happens if you swap the plug-in power supply of the Aune X8 XVIII BT for the linear power supply Aune XP2? Well, then no other device will play, but one that can be cleaned as if through a hammam and, after the massage, can go about its work with maximum relaxation. The X8 XVIII BT sounds tonally unchanged, but cleaner, clearer, even more fluid and can stage its dynamics even better in front of a quieter background. The image also gains from the subliminally perceptible lower noise level and appears more solid and three-dimensional, especially with complex pieces.

Aune X7s 2021

The Aune X7s 2021, which was primarily designed as a headphone amplifier, can also be used as a preamp like the X8 XVIII BT, and here some differences to the DAC/Pre become obvious in the direct changeover: If the X7s acts as a preamp in my chain, it makes even more sense for details than the X8. On the other hand, the Aune X7s as a pre doesn’t play quite as cleanly and smoothly in the midrange and treble and seems a bit more “nervous” than the X8. It never gets annoying, but should appeal more to listeners looking for an “exciting” and involving character.

The X7s is easily one of the most transparent and detailed headphone amps you can buy under $500, and the dimensions of the stage it projects are a touch more generous than most of its competitors in its price range. In addition, he is even more lively and, above all, a little brighter, so that the tonal classification would be a few degrees north of absolutely neutral. The bass tightens a bit without emaciating, the mids are a bit more open, and voices are a touch more top-heavy than with my Meier Audio Corda Classic headphone amp, which is twice as expensive (600 euros).

Another small digression: With regard to the choice of the operational amplifier of the X8 when operating with the X7s, it stands to reason that the combination of brickwall filter and LME49720 op-amp produces a slightly too slim, minimally high-pitched sound – and that’s it so. With the standard op amp and factory preset filtering, the sound snaps. Especially when I’m using my Denon AH D-7200(799 euros) listen. The Aune X7s drives these headphones to performances that blow me away, regardless of the price range. The minimally sonorous sound tuning of the Denon works very well with the lively and amazingly detailed sound of the Aune X7s. I am particularly fascinated by the seamless, effortless impulse and transient reproduction of the X7s – my Meier Audio Corda Classic can hardly keep up, even if it opens up a larger, more homogeneous space and is able to separate the individual sound events more clearly from one another and with more air in between.


I don’t know of any other electronics that can be so extensively adapted and upgraded with so little financial outlay. Even with the basic equipment, the Aune X7s and especially the Aune X8 XVIII BT offer very good or outstanding performance for the money, in terms of equipment as well as sound.

With the interchangeable OP amps, the universal DAC pre Aune X8 offers many tuning options, and the linear power supply Aune XP2 is a clear recommendation for “climbers” who want to tease even more out of their Aune X devices; even with the optional OP amp set you “only” end up at a good 500 euros.

The Aune X7s headphone amplifier is adaptable to different headphone models thanks to three gain stages, high power and the two 6.3 mm and 4-pin XLR outputs and brings a lively, open Class A sound into play. However, I would first listen to headphones with a bright tonality with the X7s before deciding to buy one or the other.

Together with the dynamically capable and tonally rather pleasantly “creamy” X8 XVIII BT, we have an outrageously cheap, flexible and sonorous combination for the demanding desktop listener in front of us – or a minimalist stereo system if no remote control is necessary. I’m sure: For very, very many music lovers it doesn’t have to be anymore.

The Aune X8 XVIII BT…

  • shows a tonally largely balanced sound image that only holds back a little at the absolute frequency extremes.
  • reveals a velvety, pleasant basic character with powerful timbres and a solid bass.
  • is on the ball in terms of coarse dynamics and has an impressive ability to sprint with impulses and transients in all frequency ranges, which also contributes to its fine dynamic capabilities. Gradations and gradients in this area are fluid and differentiated.
  • sets up a stage that is rather compact in all dimensions, but depicts the sound sources positioned on it in a physical, three-dimensional, tangible and clearly demarcated manner.
  • For its price range, it has a very good resolution and plays cleanly and with little distortion.
  • gains even more sovereignty and cleanliness with the Aune XP2 linear power supply and then sounds almost outrageously relaxed and natural for a device in this league.
  • offers the high-fidel play instinct a wide field to let off steam and upgrade.

The Aune X7s 2021 …

  • surprises with its lively, lively gait and the even higher transient speed compared to the X8 XVIII BT.
  • is tonally on the slightly brighter side, but does not neglect the bass range. The pressure that an X8 XVIII delivers as a player is largely retained, but appears tighter.
  • resolves outstandingly for the price range.
  • does not look bad as a pre-amplifier in a “real” stereo system.
  • depicts appropriately spacious spaces and creates air around the actors.
  • may not appear quite as clean and smooth in the mid/high range as its DAC/Pre sibling. But these are nuances – the X7s is also at the forefront of its class in this respect.
  • is extremely powerful and can be easily adapted to headphones of different efficiencies.


Model: Aune X8 XVIII BT

  • Concept: D/A converter and puristic preamplifier
  • Price: 349 euros (version without Bluetooth: 299 euros)
  • Dimensions and weight: 145 x 171 x 45 mm, 2 kg
  • Inputs: Bluetooth with aptX HD, 1 x coax digital, 1 x optical digital, 1 x USB-B
  • Outputs: 1 x volume controlled unbalanced output (RCA), 1 x fixed unbalanced output (RCA), 1 x balanced output (TRS)
  • Other: Seven digital filter modes, interchangeable OP amps
  • Guarantee: 2 years

Model: Aune X7s 2021

  • Concept: Class A headphone amplifier and puristic preamplifier
  • Price: 299 euros
  • Dimensions and weight: 145 x 171 x 45 mm, 2 kg
  • Power at 32 ohms: unbalanced output 1 W, balanced output 1.7 watts
  • Power at 300 ohms: unbalanced output 250 mW, balanced output 1 watt
  • Inputs: 1 x high level unbalanced (Cinch)
  • Outputs: 1 x headphones unbalanced (1/4″ stereo jack), 1 x headphones balanced (4-pin XLR), 1 x fixed unbalanced output (RCA)
  • Other: three gain stages, 6.3/3.5 mm adapter
  • Guarantee: 2 years