Introduction
First of all, I would like to thank Aune (@AuneAudio) for giving me the opportunity to review their unit.
This is the link to the relevant head-fi thread: http://www.head-fi.org/t/777650/aune-x1s-32bit-dsd-dac-worldwide-review-tour-reviewers-wanted.
I am not affilitated to the Aune company in any way; the tour ends with five units delivered for free to the author of the best reviews:
Five luckly winners will be chosen to get a set of X1S DAC for free according to the reviews
As you will probably notice if you will read the review entirely, I ended up liking this unit.
Of course, I would be happy to win one, but I will not try to do so by overly exagerating its good features while hiding its defects and/or limitations.
Instead, I will try to win by describing, in the most honest and thruthful way, the five days I could spend with this unit.
Please not that English is not my first language, so I hope the errors in this text will not make the reading too annoying.
Associated Equipment, including Hardware and Software
At Home
Hardware
Dedicated Mini PC with Intel Atom D510 1.66GHz (dual core, Hyper Threading)
Hardware: Supermicro X7SPA-H mainboard
Hardware: Linear PSU from italian brand ZetaGi (set @12V)
Hardware: 1x1GB + 1x2GB RAM
Software: Currently running Ubuntu Server 15.04, 64bit, Low Latency Kernel
Software: MPD (Music Player Daemon - http://www.musicpd.org)
Software: UPMPDCli (Upnp Renderer plugin for MPD - http://www.lesbonscomptes.com/upmpdcli/upmpdcli.html)
Gear
Schiit Wyrd
Gustard U12 USB Interface
Gustard X12 DAC
Gustard H10 Headphone AMP
Yulong D200 DAC / Headphone AMP
Additional software
Windows 7 desktop PC, used to run GMPC/Cantata as MPD clients and Linn Kinsky as UpNP control point
BubbleUpNP on Android as UpNP control point
Another Debian-based Linux box is dedicated to file sharing (via Samba and via MinimServer, a UpNP server)
Cables
USB Cables: Audioquest Cinnamon 0.75m
HDMI Cable (I2S), used for the comparison with Gustard U12/X12/H10: Ricable HDMI Supreme F1
Balanced Cables, used for the comparison with Gustard U12/X12/H10: Neo By Oyaide D+ XLR
Headphones and Speakers
Headphones: Sennheiser HD650; Sennheiser Momentum On Ear; Denon AH1001; Yamaha HP-3 (Orthodynamic, modded)
SMSL SA-50 amplifier
JBL Control One speakers.
At the Office
Linux PC with Intel Core2Quad Q6600 @office, also used with MPD (Music Player Daemon - http://www.musicpd.org).
Headphones: Sennheiser HD650.
Unboxing
The first thing I noticed, looking at the box, is that the Aune brand is symmetric. Nice!
I then realized (after reading WayneWoondirts' review) that I was not the first to notice this curious fact. Still, that reading led me to know the Aune logo is actually an "ambigram" (https://en.wikipedia.org/wiki/Ambigram): I didn't even know the term. Thanks, WayneWoondirts.
The box is appropriate in size, everything has its place. Sometimes happens that when you need to put everything back, you wish you had a bigger box. Luckily this is not the case.
The PSU is 220V, and has plugs suitable for my area (Italy). So no adapters needed: good!
The other thing I immediately noticed is the nice design of the DAC itself. My wife liked it, too.
Description
The unit is quite small, and can fit nicely on most desktops. It feels very sturdy.
The PSU is quite big and bulky, but luckily its conformation does not require to connect it directly to the wall, having a power cord (non detachable) instead, on both sides. The cords are long enough to comfortably place the PSU away from the desk area. So no big issues here.
The side panel curves are similar to the one on the volume knob: a nice touch! The unit IMO is aesthetically very pleasing.
Its curved top surface might be an issue if you plan to stack something on it; of course, you can stack the Aune X1S on other (supposedly flat) unit without issues. During my tests, I stacked the X1S on a Yulong D200.
The volume knob itself, while it does not offer a lot of resistance to the rotation, feels well implemented. During the listening session, I did not notice any amount of channel imbalance.
The front panel is very simple: a simple selector (which also controls the active filters), the headphone 6.3mm socket and the volume knob. A 3.5 to 6.3mm adapter is included.
The Aune gets only slightly warm even after many hours of usage.
On the back side, you can find the usual power connector, the USB type B socket, two SPDIF inputs (Coaxial and Optical), a Coaxial output (quite unusual on this kind of products). Also, there is a couple or RCA analog output (fixed level) as well as a couple of RCA input.
So the unit can be used as a DAC alone as well as a headphone amp alone.
Some people complained about the analog output being fixed: if you want to connect speakers, you need either an amp (as in my case), or powered speaker with indepent volume control.
Of course, if the output had been variable, someone would have complained because it is not fixed. You can't please everyone.
Very few DACs have both variable and fixed outputs. Personally, I prefer the fixed option because I use an amp to drive my desktop speakers.
Also, implementing both options would surely raise the final price, so I think Aune made the right decision.
Specifications
I do not want to replicate the specifications page you can find on Aune's site.
What's worth mentioning, and what probably people expect to find in a review, are the supported formats and the adopted DAC chip.
The DAC chip is, accordingly to the specs, a Sabre ESS9018K2M.
The device supports all sampling rates up to 384kHz (including 88.2, 176.4, 352.8 as well as, of course, the usual 44.1, 48, 96, 192).
The setup
All listening tests were made using the mentioned dedicated Linux box with mpd, either with the mediation of upmpdcli or natively.
The Linux box also benefits of a Schiit Wyrd, which supposedly "cleans" the usb signal and has its own separated power supply, isolating the DAC from the noisy PC environment.
In my experience, the use of the Schiit Wyrd is very effective, altough the improvement is less evident when used before a dedicated interface like the Gustard U12. I consider the Schiit Wyrd one of my best audio purchases ever.
I find the Linux setup so clearly superior to the Windows counterpart that I do use the latter only occasionally: the Gustard X12 is connected via usb to the desktop PC, while the Gustard U12 is connected to the Linux box, with the Schiit Wyrd in the middle.
I also used upsampling @352.4kHz and @384kHz with sox, alternated with a more native configuration (a.k.a. bit perfect).
Another advantage of using Linux is that you do not need to install any driver. Using multiple dacs on windows can be very annoying if not a nightmare. Try dealing with 3-4 XMOS control panels that all look the same (distinguishable for the different version numbers, when you're lucky enough) one for each XMOS based DAC you ever connected.
Definitely not funny. Not so with Linux!!
So, I did not use the usb flash drive at all. However, it is a nice touch, since it is more likely that new PCs do not come with an optical drive.

The Tracks
For this review, I mostly used the following tracks:
Carlos Santana - 'Aqua Marine' from 'The Ultimate Collection'
Miles Davis - 'So What' from the 1959 album 'Kind of blue', purchased on HDTracks (24bit/192kHz)
Eric Clapton - 'Tears in Heaven', 'Running on Faith', 'Layla', and really most tracks from the 'Unplugged' album
Dire Straits - 'Money for nothing' and 'Brothers in Arms' from the omonimous album; 'Fade to Black', 'Planet of New Orleans', 'My Parties' from the album 'On Every Street'
Janine Jansen - 'Le quattro stagioni' (Antonio Vivaldi), purchased on HDTracks (24bit/96kHz)
Rebecca Pidgeon - '24 hours of love', 'Primitive Man' from the album 'The New York Girl's Club', also purchased on HDTracks (16bit/44.1kHz only, sadly)
Sting - 'Consider me gone', Moon over Bourbon street', 'Fortress around your heart' from the album 'The Dream of the Blue Turtles'; 'They dance alone', 'Little wing', 'History will teach us nothing' from the album '... Nothing like the sun'
All the tracks come from flac files ripped from my precious personal CD collection with Exact Audio Copy, except when otherwise noted (HDTracks downloads).
Of course other tracks were used, these being the most relevant ones.
I also used some demo DSD tracks to test the functionality with each and every possible operational modality (e.g. all sample rates) of the X1S.
The Listening
Now, the fun part. I prepared a short playlist and connected my faithful Sennheiser HD650 to the Aune X1S.
The first listening was really a pleasant surprise! I did not imagine to be gratified by a sound so detailed, rich and non fatiguing. Also, the soundstage is so immersive.
Listening to Santana's 'Aqua Marine' was real good. I used this track multiple times during the comparisons with my other systems. A great sense of depth was clearly perceivable. It was a please to hear fast changes from quite to loud passages.
Miles Davis' 'So what' from HDTracks @192kHz flows nicely and natural, an incredible track. Miles' trumpet is very real and I had the impression to be present in the recording studio.
Eric Clapton's classical 'Tears in Heaven', 'Layla', 'Running on faith' from 'Unplugged' (as well as all the other tracks: that album is really amazing...) sound live, detailed, vibrant and dynamic as they should. Some background noise, present in the tracks at times, tells the listener how natural the recording actually is. It feels like you can see Eric touching those strings and tapping his feet.
'Le quattro stagioni' played by Janine Jansen are fast, detailed and dynamic. Again, this recording is live and natural. The player's breathing is clearly audible, the violin sound is so sweet and natural, while the continuous bass sustains the performance wonderfully.
I also especially like the indicated Dire Straits' tracks (as well as many others) for the clean and elegant executions. In particular, while 'Brothers in arms' is one of the tracks I always greatly enjoy, the tracks from 'On Every Street' are exceptional in the quality of the execution, so lush, warm, expansive. The Aune X1S renders them very well! It is a very relevant test for me.
The same mostly applies for the Sting tracks. In particular 'Fortress around your heart' is a best favourite, for the nice soundstage with instruments' positions so definite. Also, I like Sting's voice a lot. I enjoyed a nice refined reproduction with the X1S.
During the tests, I used other headphones too.
In particular, the Sennheiser Momentum sounded very nicely with this dac/amp. I know how easily the Momentum can play with a really bloated and confused bass if the amplifier has non-optimal output impedance. In particular, they sound almost unlistenable with the SMSL SAP-III, which is in fact targeted to high-impedance headphones. In case you wonder, no, there is no comparison between the SMSL SAP-III and this Aune X1S. The Aune X1S is simply in another league.
I also used the Denon AH1001. No surprises here: these are decently sensitive headphones (more than the Momentum On Ear, or maybe their isolation is better, or maybe both!). Decent neutral sound.
The Yamaha HP-3 are not very sensitive and are around 150ohm of impedance. In my opinion, the X1S lacks some power when driving those. Still, it drives them to good levels, but something is missing.
I also used, for a small amount of time, the SMSL SA-50 amplifier to drive the JBL Control One speakers. No surprises, the sound was nice, deep and detailed as expected.
So, is everything ok and aligned to the expectations, and even beyond? Sure. The Aune X1S seems a perfect companion for serious headphone listening.
Does it smash any competitor in any category? Well, not so fast...

Comparisons
Of course, I compared the Aune X1S to my other gear: the Yulong D200 and the full Gustard Stack (U12/X12/H10).
The Schiit Wyrd was used for ANY of the mentioned configurations.
Versus the Yulong D200 DAC/Headphone Amp
Compared to the Yulong D200, the X1S performs very well. The detail on the D200 is a hair better IMO, and the sound signature is quite similar (after all, they are both ESS Sabre Chips, ESS9018K2M for the X1S and ESS9016 for the D200). Where the D200 shines against the X1S is the output power, which is probably responsible for tighter bass. The D200 has more body and handles dynamic passages with more ease. It feels like the D200 has more 'control' on the music.
Of course, it's a bit unfair as a comparison, as the price of the D200 is more than 2X the price of the X1S.
Versus the Gustard Stack (U12/X12/H10)
Where there is not chance for the small X1S is when I compared it to the Gustard Stack. Simply, the Gustard stack is on a higher level. More power, more depth, more details. Almost every aspect is inevitably better on the Gustard stack. In this case, again, the comparison is sort of unfair. The Gustard stack is composed of separated interface, dac and amp. The size of the kit is enormously different and the price is about 4x the price of the X1S.
But, paradoxally, it was this test that showed me the real value of this X1S: for 1/4 of the price of the Gustard Stack, the performance is surely enjoyable and pleasing. In fact, like other uses, I think the X1S has considerably raised the bar of 'entry level' quality, and that's really a good thing. Further competitors in the 200-300$ price range will have to be able to at least not disappear against the X1S.
Versus some other Stuff
At the office, I am using my FiiO X5 as a usb dac with a Epiphany Acoustics O2 headphone amplifier. In this case, yes, the X1S is clearly better. Awesomely better. The X1S has more functionalities (up to 384kHz sample rate support, and DSD support), more quality, more detail, wider soundstage, more power, a nice pleasant design. More everything.
Plus, it's a one-piece kit, perfect for office use.
Previously, I was using a SMSL Sanskrit with a SMSL SAP-III (mentioned before). No contest here, the X1S beats this kit hands down.
Concerns about the PSU quality were expressed on Head-Fi.org
Some users expressed concerns about the PSU quality. They say the stock PSU is a SPSM, and therefore not suitable for an audio device. AFAIK, a SPSM is not bad per se, but usually a linear power supply should be a better choice. That said, it seems to me that adopting such a PSU would have raised the price of the X1S considerably.
Still, in case Aune decides to disclose the specifications of the PSU (which seems to me to be dual, but I am no expert), adopting linear PSU might be a nice upgrade.
Anyway, I did not notice any issue that can be related to the PSU: no background noise is audible to my ears, and it seems that the PSU is good enough. I don't know for sure if a different PSU solution would add some grunt to the amp module.
Conclusion
Again, I want to say "Thank you" to Aune for the opportunity of having the X1S for some days of testing.
The Aune X1S is a very nice concentrated of audio technology. It will surely please anyone looking for a compact all-in-one solution in the 200-300$. I cannot make comparisions with stuff I do not own, but considering how close it is to the Yulong D200, I think its value can surpass many if not most current DAC/AMP in the 300-500$ range with ease. It is just an speculation, but I am quite confident of it.
The X1S is detailed, powerful enough (unless you use very difficult headphone: I think, for example, that the HifiMan HE-6 are out of reach here), it offers a good soundstage, and delivers hours of non-fatiguing listening pleasure. Definitely a bargain for the required price.
Congratulations Aune, well done.