Aune S6: warm, thick, impressive low end grunt

Pros:  Full bodied sound, nice information display, balanced inputs and outputs, digital numeric volume display

Cons: single-ended sound is foggy, soft treble, only DSD128 (DoP), volume control has no feel to it, could have more bass and treble extension

List Price: $569 (Penon Audio, affiliate link)

Product Website: http://en.auneaudio.com

Aune S6

Rating Disclaimer: ratings are subjective. Audio quality and value do not mean the same thing across all prices. A headphone with a 5 rating on audio at $5 does not have equivalent sound quality as a 5 rating at $500. Likewise, value at $5 is not the same as value at $5000 dollars.

Introduction

I started my relationship with Aune Audio (Ai Lo Er Science and Development Co., ltd.) via proxy. Penon Audio had announced on Facebook that the Aune M1s was coming out, and I thought it sounded like a just about perfect budget DAP. I contacted Penon Audio for a review unit, and talked to Aune Audio about doing a tour on Head-Fi, as they were a sponsor there. From there the official tour kicked off and several Head-Fi reviewers got to enjoy the Aune M1s. The M1s still rates highly as a neutral DAP that does well with all IEMs (not demanding cans). I still use the DAP for reviews for its neutrality and flexibility. It is a no nonsense, pure music, great reference DAP. When it goes on sale for $199, it’s also a great priced DAP (more competition at $250).

I came across the Aune S6 via similar route. I was asked by a third party with a good relationship with Aune to be the final leg of a Head-Fi official tour and keep the unit for review at the end. This unit was with many people before me, so it got a little wear from being packed and shipped and packed and shipped. After my experience with the Aune M1s, I was more than happy to help out.

Usability: Form & Function

Unboxing

The Aune S6 comes in a big black paper box with Aune written across the top. The box is a single-wall two piece box like an unhinged shoe box. This means that to open it you have to wiggle the box lid upwards, same to close it. This isn’t too hard when the weight of the DAC is inside, but it’s a pain in the butt when it isn’t. When writing this review, I couldn’t remember what the layout was like inside the box, and when closing it back up minor misalignment caused a tear in a corner. The box is held together by tape. This box design needs to go. I would have preferred that the box be thicker, with a hinged design. I can’t be sure what kind of box would come around this inner box at retail, as this one came on a tour. But given the number of layers of tape on the outer box and the remnants of a DHL (best Asian shipping option) label baggie, it appears to be the original box that Aune sent for the European tour. The outer box is a thin single-wall box that is not confidence inspiring. The thinness of the two boxes is probably okay, though, as inside the inner box there is a substantial amount of good quality dense foam to protect the unit. I think that the lower and upper foam padding probably should be a little thicker, but it may not be necessary given that the DAC isn’t terribly heavy. The package made it here safely through several shipping legs, it is unlikely that there would be a problem for purchasers.

Inside the box there is the DAC/Amp, a business card, a power cord, a USB cable, a 6.3mm to 3.5mm adaptor, and a USB drive (containing driver and e-manual). You don’t normally get a USB cable, 6.3mm to 3.5mm adaptor or a driver dongle in these packages, so those are nice touches. You have everything you need to get listening right out of the box, nice.

Features

 

40233216061_edc46182b7_bThe S6 has all the digital inputs you could want: AES, coaxial digital, and optical digital (all limited to 24/192); and USB (32/384 PCM, DSD128 in DoP). The S6 does not play DSD natively, instead using DSD over PCM (DoP), which essentially puts a PCM wrapper around the DSD content. The S6 has balanced (dual 3-pin XLR) and single-ended (RCA) line level outputs with 2VRms (pretty standard voltage) on the RCAs, and 4VRms via XLR. For headphone outputs your get a balanced 4-pin XLR and a 6.3mm single ended output. The power output of the S6 is listed at 246mW for the balanced out, and 72mW for the single ended, the load characteristics were not listed—is it 32Ω, nothing, 300Ω? After looking online at Shenzhen Audio, it turns out that the load statistics are for 300Ω. To allow people to compare a little more, that translates into about 2.3 watts with a 32Ω load (linear power assumed, often not true), which is a bit of juice. The Questyle CMA600i has a 1.9 watt rating, but also has the magic of current mode, so probably gets a bit more powerful.

The front fascia of the Aune S6 has a large and very useful display that tells you the volume level, which input you are using, which output you are using, and what type of music you are playing. To the right is the multiple use control knob. By pressing in once you can change input. Pressing twice changes the output. Holding the knob for five seconds turns the S6 off. Of course, turning the knob adjusts the volume. Volume scales from 0-100. I found the volume knob to feel cheap. It has no resistance to it, it’s like the kind of knobs on children’s toys that just turn freely. It doesn’t feel high end in any way. It won’t be winning any knob feel awards, that’s for sure.

The power supply of the Aune S6 is a switching power supply, but the switch is internal and changing the voltage voids your warranty—internal switches are dumb. The warranty isn’t that long anyway, so meh.

Image from the Qobuz review of the Aune S6

The mighty hedgehog of Headfonia, Nathan Wright, used the Susvara in his review, which surprised the heck out of me, so I tried it. It drove it. Now I have to talk about this in the sound section below. Impressive and disappointing at the same time. That’s a lot of drive, but Nathan just made me have to do extra work. I tried the ADV Alpha out of the S6 balanced jack. Don’t do it. The balanced out doesn’t drive it. I don’t know why this is. The single ended output drives it, but isn’t good sounding (afterthought city on the SE side). When the ADV Alpha is hooked up to the balanced jack it is super quiet, and strains the amp into clipping. I’m concerned that trying to drive it might be dangerous. I think this could be due to high output impedance on the balanced output, but I’ll leave it to someone more knowledgeable than me to explain it.

Fun with drivers

I had half of this review written on a Windows 8 PC that then was lost with a piece of luggage. Installing drivers on that machine worked fine. All I had to do was download the file and install. Easy peasy. Windows 10 is also easy, but not in the way you expect.

I installed the drivers. First time round, I was warned that the drivers weren’t signed and stopped dead in my tracks. So next time, I ran as administrator. The driver didn’t show up in JRiver. I restarted and did another install. Then the USB started going off and on with the connecting and disconnecting sounds cycling (like when you have a faulty USB). Then I gave up and uninstalled the driver all the way down to the registry.

For fun, I just plugged in the S6. Windows 10 did its thing and now it works. Easy.

Don’t install the driver from Aune if you are running Windows 10. Just plug it in and wait.

Audio quality

The Aune S6 has a rich tonality with a bit of emphasis in the mid-bass and lower mids. You could definitely describe the amplifier as warm. I’d describe it as delightfully beefy. The soundstage is good, but nothing special. Detail resolution scores similarly to the soundstage. These stage and resolution characteristics often come hand-in-hand with amplifiers on the warmer end of the spectrum with north of neutral mid-bass.

Do the can can (headphone play)

Focal Utopia (Atlas Zeno dual 3-pin XLR to Vertere Acoustics 4-pin XLR adaptor)

Using the Focal Utopia, the Aune S6 was less detailed than the CMA600i. Listening to 2Pac – God Bless the Dead, the bass has great body on the S6. Deep and bold. Nice. The S6 drives the Focal Utopia with plenty of headroom. Compared to the Questyle CMA600i, the stage is more forward with less depth on the S6. The S6 still allows picking apart the image, with the excellent resolution characteristics still showing. The S6 isn’t quite refined enough for the Utopia. The mids aren’t as clear on the S6 as on the CMA600i, but the CMA600i is three times the price, so some differences are expected. The CMA600i is better, and it should be.

HiFiMAN Susvara (Atlas Zeno, 4-pin XLR)

I also brought out the Susvara to play on the Aune S6, due to the aforementioned hedgehog and photographer, Nathan Wright. I volume matched the Aune S6 all by itself, versus the CMA600i feeding the XIAUDIO Formula S. I used an SPL meter and marked each at 72dB using white noise, which is actually a bit louder than I’d normally throw down (but not by measurement). Open back headphones are hard to measure, my normal listening level is 78 dB and its normally quieter than this. I’m pretty sure I’ve got less than 0.2 dB variance between the measurements though. Switching is pretty seamless. It takes every bit of the Aune S6’s amplification power to get to this level. I’ve got the knob set on 97 out of 100 on the S6. To it’s credit, it stays clean all the way up to this level. I think it’s distortion performance on the balanced out is probably pretty dang good.

Listening to Michael Jackson – Billie Jean, the dynamics are good on both amps, but the power of the Formula S is readily apparent in the track when switching. The S6 actually does a really impressive job on this, it’s more than listenable, it’s excellent. The margin between the Formula S and the S6 is not as large as you would expect. The soundstage on the S6 has less depth and width, but the difference is modest. When resolving bass notes on Billy Cobham – Quadrant 4, the bass is rich on both, but has a bit more texture and nuance on the Formula S. The midbass is a bit more pronounced on the S6, but I think this may be due to the Formula S’s capability to pull out more detail in lower end of the bass. Quadrant 4 is a complex track, the Formula S keeps the complexity just a little bit cleaner and delineated. On Slayer – Necrophobic there is more air around the instruments on the Formula S and greater control across the frequency spectrum, more nuance and detail bleed out of the Formula S presentation. The sound is more crisp and defined. The S6 still performs well, given it just shouldn’t be able to play on the same planet as the Susvara as a <$600 DAC/Amp.

HiFiMAN HE-1000 V2 (Atlas Zeno, 4-pin XLR)

I compared the HE-1000 V2 on the Aune S6 and the CMA600i. Since the Susvara listen felt too loud, I decided to drop the dB on the SPL from 72 dB to 68 dB. That’s much better. I recently ripped my white noise WAV files to FLAC, maybe this has something to do with the difference I’m noting? Maybe it’s just open full-size headphones versus closed in-ears?

On Rush – Spirit of the Radio (MFSL CD) the S6 sounds a bit more dynamic. It has more energy in the treble, and a bit more body in the mids. It has a little bit less stage depth than the CMA600i. The instrument separation on the CMA600i is also superior on Slayer – Necrophobic. With Leonard Cohen – Leaving the Table, the lower mids are smoother and a touch warmer on the S6, but not as detailed as the CMA600i.

Sennheiser HD600 (WyWires Red, 4-pin XLR and with XLR to 6.3 adaptor)

The S6 handled both the Susvara and the HE-1000 V2, so on driving power, this should be easy. For this test, the single-ended output and balanced output will be compared. In all instansces the same cable is used, with the adaptor a WyWires red adaptor. All volumes were level matched at 78 dB using white noise and an SPL meter. On the S6 this corresponds to a volume setting of 63 in balanced operation and 74 in single-ended operation. The CMA600i was at roughly 10 o’clock on the volume knob.

Single Ended vs. Balanced

Bass sounds a bit tubby on Spirit of the Radio listening in single-ended. The overall sound is course with little depth in presentation. It’s a terrible presentation of the HD600 frankly. The HD600 is known for it’s liquid mids, and the botched single-ended presentation here doesn’t allow the headphone to sound like itself. This is a serious failure. I wasn’t sure where to dock this fail in my overall rating, so I gave a pretty big hit to the build quality score. The way I see it, failing to implement equal quality across single-ended and balanced is a design failure.

When switching to balanced operation the real HD600 shows up. The overall presentation is smooth with those famous liquid mids on Stevie Ray Vaughan – Tin Pan Alley. The failure on the single-ended is pretty epic, especially considering how good the balanced output sounds. The balanced output puts a little more beef on the lower mids through midbass giving the HD600 a little more body. However, when switching to the CMA600i, there is more texture to the same bass notes. The technical performance edge goes to the Questyle CMA600i, but the S6 has some good soul.

Specifications

I don’t normally make a comment about published stats—I used to more, but the stats for the Aune S6 are very incomplete. The power output for the headphone outputs doesn’t tell what load resistance the measurement was taken at in online specs (I had to find it at Shenzhen Audio). It is not likely that the balanced line-out and the single-ended line-out have the same statistics. Same with the headphone output stats on THD+N. I think Nathan at Headfonia did some measurement, but it isn’t clear. Also, when I checked the stats on the Aune M1s, most of the reported numbers were exactly the numbers of the Sabre chip inside it, which means that Aune may not be doing much in the way of measurement. Sabre’s stats would have been under ideal conditions.

I think the specifications table below should be taken with a grain of salt. This probably isn’t what the S6 would measure in an independent lab.

[rant]

Why aren’t there independent labs doing measurements for equipment? This seems stupid to me. With all the variance in measurement technique, there should be independent labs that do measurements with an agreed upon and publicly disclosed methodology.

[/rant]

Specifications
Price $569
DAC AK4495SE
Audio Formats 32/384 PCM, DSD128 (DoP) over USB, 24/192 PCM (coax, optical, AES)
Dimensions 28.8cm (width) x 21.1cm (depth) x 6.3cm (height)
Accessories USB cord, USB drive (with manual and drivers), power cord
Line outputs
Frequency response 20Hz-20kHz ± 0.4dB
Dynamic Range 116dB
SNR 115dB
THD+N 0.0008% @1kHz
Crosstalk -132dB
Output level 2Vrms (RCA), 4Vrms (XLR)
Headphone outputs
XLR 246mW (1kHz @ THD+N 0.001% into 300Ω)
6.35mm 72mW (1kHz @ THD+N 0.001% into 300Ω)

Acknowledgment

The Aune S6 was provided to me free of charge by Aune. I do not have to return the unit, but am not free to sell it or give it away without express permission. I have received no compensation for this review and the thoughts contained within are my honest opinion. Thank you Aune for supplying the review unit.

Conclusions

If you are a fan of a rich warm sound with some extra bass body and good driving power, the Aune S6 might be good for you. It has a slightly warm, inviting sound with good detail levels. The amplifier has something in common with most integrated speaker amplifiers, the single-ended 6.3mm output sucks. If you are buying this, you are buying it for the balanced output. You’ve been warned, and Aune has been given de-merits in the ratings.

The Aune S6 has some quirks that may turn off some, such as the curved top, the loose feeling volume knob and the basic screen. Personally, I liked the screen. I also liked that it had strong output from the balanced XLRs on the back. It comes with the who’s who of connectors on the back, so you won’t be short for usability.

This is a good all-in-one headphone amp/DAC/pre-amp. There are a lot of good units of this variety now, and more entering the market all the time. This one has more driving power than most, and is definitely worth a flyer when it goes up on Massdrop.

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