Great review Alex! I think I will recommend this to my entry audiophile fellows! Seem like a very well rounded entry DAP. 
Well, until something else comes up.

Very good review!
 
I like the in-depth analysis and I am looking forward to hearing one myself, and most of all things I am looking forward to Fiio x7, your review fueling my once dead passion to replace my DAP. (I was really happy with my Fiio X5II).
 
But the way you put your thoughts into words, you really made me be back at it with DAPs, and for this I am grateful ! 
 
BTW, The only downside for this, if someone is deciding between this and X5II seems to be touch vs wheel, thing which again is great because it will push DAP makers to build cheaper, better DAPs!
 
Congrats, 
George

@JohnYang : there is always something new and exciting around the corner I'm looking forward to
 
@Dobrescu George : indeed, you're no longer have to spend $2k or even $1k to get something that sounds great.

Damn, there's always a spiffy new toy on the market that I "can't live without" but can't afford, either. I'm a proud owner of a DX90MM and the only other non-iPod DAP I've ever heard: a FiiO X1. I have no idea what the X5(ii) or X7 sound like and I'm so happy with my DX90 that I'd decided to stick with the brand I know and love rather than jump ships with my next purchase. Now you've given me reason to question that decision, which I both love and hate.
 
What I really want to see now is comprehensive reviews of the stock DX80 from folks who also own a hardware-modded DX90 like mine, because if the newer model's SQ isn't obviously improved in some way then it makes my next DAP purchase a bit more obvious.

Have you tried to play 24b/192k by yourself? I tried to play 24b/192k FLAC and output is silence, no sound at all,  the same as DSD playback. I googled, Coax/optical cannot pass through DSD or 24b/192k, only 16b/44.1/88.2/96k. I did not see optical/Coax useful If no further firmware to add settings like this Optical/Coax output ( Native or convert to 24/88.2k ).
>>>>>>>>>>>>>>>>>>>>>
 Last, but not least, is SPDIF Coax port which also has an Optical out – enabling output of up to 24b/192k signal.

It is limitation of bandwidth from Optical/Coax output , not ibasso, but new firmware should provide alternative better solution like settings Optical/Coax output ( Native  or convert to 24/88.2k ), because actually Optical/Coax output cannot not pass through 24b/96k or DSD above.

excellent review, as always.

how do u use R70x to dx80? is straight to HO or add an amp?

@and132 : no need for an amp, and I had DX80 in low gain - straight to HO and it sounds great!

How did you get the USB OTG to work, and what flash drive did you use.

@scottru : it works by default, gets recognized automatically (after all, it's an android based os).  The drive I was using is an old Sony usb otg drive, they don't make those anymore, but if you go on Amazon and search for "usb drive otg", you will get a ton of choices from Sandisk, Kingston, and others.  They are small thumb drives with both full size usb to connect to your laptop to copy files and micro-usb with built-in OTG to connect to your smartphone, or DX80 in this case.  There are also small usb otg card readers that host micro-SD card.

I am out of luck with my DX80, I have applied the latest firmware update and I am using a 64GB Sandisk OTG drive.

When you mentioned the packaging in the beginning of the article, that struck a note with me. I worked as an engineer for a company that produced packaging equipment for production lines, including those blister packs everyone hates.but we would have customers come in with requests to package something in some very special packaging like the one for this product, and our answer was always the same - go hire somewhere between 10 to 300 people, and put them to work, because this can not be automated. So, in a way, this does show that a company has put some extra care into the packaging because they had to hire manual labor to do this, and do it to perfection, and fast. It was not unusual to see crews with white gloves packing up things like this, and depending on how fast they were running things, it could be several hundred people there doing it. So, it is not cheap or easy to pack things this way, and it is simply done to improve the image of the product, and add a sense of implied value, which it actually is, because they paid much more than normal to do it that way. We had a customer that made high end cosmetics, La Prarie, and they showed up one day complaining that our equipment was not functioning on their new product. I went out there to look at it, and they had designed a box within the physical specs for our machines, but they had designed the box backwards. They had printed and bonded a sheet of holographic logo film to laminate to the box, which our machine was not designed to handle. It was designed completely backwards, and the manufacturing people all said that it was the CEO's project, and she did what she wanted. We had no glue that would seal it, and it was impossible to even run them through the machine without leaving a small mark on it, which she was not having at all. Since they had paid dearly for equipment from us, and were on line to buy more, my boss asked me to stay and advise them on how to do it by hand. We ended up hiring 150 temps, buying 50 workbenches and 400 yards of black felt to cover the benches, and white gloves for every worker, and having to get an engineer from Loctite in there to help formulate an adhesive that would work to glue the boxes. The CEO came down to check on the progress one day, and I mention the added cost. She said "Honey, women pay me $750 a bottle for this stuff. If I wanted to use real gold lids on the jars instead of crystal, I could do it, and still not lose money. You just make sure every single box is perfect."
Also, Re: the non-replaceable battery. If Ifixit.com has taught us anything, it is that there is no battery that is non replaceable. It just depends on how skilled and brave you are when it comes to getting in there. As far as blaming Steve Jobs, it is not his fault. If you want sleek and thin, you can not make it easy to open. But people have been changing the batteries on Apple products since they started making them.

Very nice review!  Great job.
 
I am quite a newbie when it comes head-fi.  However I can appreciate a good product when I come across one.  ibasso certainly redefined the "high quality / reasonable price" market segment.  I am a happy owner of basso's DX50/90 and now DX80.  I got the DX50 quite late so I did not have to deal the firmware saga when it was first introduced.
About the sonic differences between these DAPs, I would say that the DX80 is a big step up from the DX50.  To my ears, the DX50 has a very flat presentation, kind of like music in your face like it or not.  With the DX80 I can hear a lot more layers and much better instruments separation, much better quality from top to bottom.
With the DX90 its a lot closer.  To my ears, the DX90 has a more analytical presentation.  More extended highs but a tad drier.  Bass is firm and goes low, but not as much when compare to the DX80.  Mids of the DX80 is more forward and with it brings a fuller and warmer sound.  More organic when comparing with the DX90. Overall, in my opinion DX80 is a more "musical" DAP than the DX90.  I came to this conclusion after trying both phone out and line out of both DAPs.
However, just like food, everyone has different taste, I actually prefer the signature of the DX90 for its more analytical sound.  This may be due to fact that I'm almost a pure classical listener.  I have lots of different recordings of the same piece of music.  Therefore I'd like to hear as much straight out of the recordings as possible.
Also it will depend on what iem/headphone you pair them with.  For me, the DX80 works wonders with my ER4S.  Aside from HM901 from hifiman which cost a whole lot more, the DX80 can really bring the life out of my otherwise boring ER4.
However, when I'm using my HD25-1ii or DT1350, I prefer using the DX90 because those cans already have plenty of bass.
All-in-all, I think the DX80 is an exceptional price/performance piece of equipment, and is very capable of challenging other DAPs that are two to three times its price.

Great review. You rock Alex!

Super useful, as usual twister6.  It`s a shame neither DX80 at iBasso`s table were functioning at the last Tokyo headphone show . . .   I liked the DX50; the DX80`s form factor is much better. 

Really thorough review, which has inspired me to get a DX80 on top of my DX90.  I need a new, reasonably priced DAP that has greater storage capacity and an larger/easier GUI.  I like iBasso's support and business model, and was waiting for this to come out, and now feel confident that this will be a more functional device for my portable music needs.  Thanks Alex!

Alex, I thoroughly enjoyed that review.  Thank you so much.
 
I am a very happy long-term DX50 owner.  I will probably upgrade to the DX80, but now sure how much of a hurry I'm in.  Biggest draw to me is the 2 card slots.  I have one card that I always put new music on it and swap them around as i listen to them.  It would be great to have a static card with long term music, and one for transitory (new) music.
 
I was also interested in @nzvlam 's comment about DX50 having a flat presentation.  I have the Chesney hair clipping recordings, and can't really tell a difference in depth and height as they are moving around my head.  Not sure if it is my ears, or possibly the DX50.  If I can get better soundstage out of the DX80, that would be cool too.

great review Alex. I have the DX90 and love it. Cant wait for the DX200 t come out,that will be a flagship DAP.

Wonderful review! I was wondering if you could elaborate a bit on Sharp/Slow roll off. I noticed you used Sharp when doing your comparisons. TIA

@KC33 just going by memory since I'm not next to my DX80 at the current moment, the filter roll off affected speed of a sound just a bit, very subtle to the point where you might not even notice, depending on which headphones you are using (more noticeable with faster BA drivers).