This Aune's player is almost not-know on Head-Fi, but it is very interesting device with exceptional sound quality for its price, so I've decided to write my brief impressions. English isn't my native language, so I'm sorry for some possible mistakes, and for not being as interesting as other Head-Fi reviewers
I don't know why, but some Aune products became extremely popular on Head-Fi (like T1), while others remain pretty unknown, regardless of their exceptional quality. Their first DAP, M1 leaves really mixed impressions. On the one hand, its sound quality is really impressive, especially for $150 price, on the other hand, it have lots of really noticeable shortages.
But first of all — exterior.
Player is sold in small white cardboard box, very similar to Apple iPhone's box. Inside you got player itself, coaxial output adapter, micro USB cable for charge and manual. That's all. It's not the fanciest accessories set, but for M1's price, this player is OK.
M1 itself is very solid device as it's made completely from black anodised aluminium. Size is 103,1 mm x 56 mm x 20 mm, weight is 181 g. Aune M1 not the smallest DAP, but it fits nicely in hand, because width is less then average.
On top panel you'll find headphone out, coaxial out and analog volume volume regulator. Out of the box it was set to zero, so I've spent few seconds trying to figure out, why there is no sound. On bottom panel you'll find SD card slot, LED for battery indication and toggle switch for turning M1 on and off. M1 doesn't have power off feature, so you should always remember to turn it off, to avoid battery drain.
Official specs told that M1 suppord SD cards up to 32 Gb, but some 64 Gb works too. One of the biggest device's disadvantages — it's very whimsical when it comes to SD cards. Some of them work, others don't and I don't know, is there any consistent pattern. So, it's better to try SD card before buying. Other player's feature — it won't turn on without SD card. But this decision is pretty logical, what to do with player if no music is found?
On front panel you'll find all other controls: 5 buttons and screen. Player firmware is really simple. It can play only WAV files and only 44.1/16 resolution. When you turn M1 on, you see your card's contents, you select folder, it plays. That's all. No cover art, no sleep timer, no bass/treble selection. Absolutely no options. Only available option is paly order, it can be switched with dedicated button and chose to play songs one by one, in random order and so on. On the screen you'll see song title, play time, battery status and that's pretty all. From "additional features", M1 offer .CUE support, but it works not with all files (at least for me). Positive side — M1 boots up really fast, after flicking the switch it takes just few seconds.
To reduce power, M1 enters "sleep" mode after approx. 30 seconds of inactivity: turns screen off and locks buttons. To turn it on again, you need to press rightmost button.
I know, everything described above, sounds devastating. But M1 offers one really great feature — its sound.
Stock M1 build with PCM1793 as DAC and NE5532 + OPA2134 as amplifier. It's able to push 700 mW into 32Ω load, and it's pretty good amount of power for most of the headphones. DAC and amp placed inside on replaceable board, and Aune told that they'll release other DAC, but I have doubts about that. Anyway, stock sound is really superb.
M1 sound really neutral and natural. It have both transparency and musicality. Bass is really nice, it's punchy, it's energetic, well controlled and goes really deep. Mids are detailed and emotional. Highs are also transparent and well controlled, but sometimes I miss their quantity a little bit.
Overall, soundwise, I'd place M1 above Fiio X5 and iBasso DX90 (just my oppinion), M1's sound is just more natural, and good amount of power helps it shine.
There is spare module, made by thirdparty developer from China, based on CS4398 (called Modile Choir [http://tw.taobao.com/item/40367662569.htm?fromSite=main]). It's also sounds really interesting, but with less of energy in sound. Choir's sound is more like QLS360, with absolute neutrality, with spacious sound stage and more resolution.
With full battery, M1 is able to play for 7 hours, really nice for such a powerful player, and it takes about 2.5 hours to charge it.
To conclude, Aune M1 is really lacking lots of modern features, but it offers outstanding sound quality for small amount of money, so if you want really good sound — it's worth trying.