Now that I have had the DX80 for a few days, I guess I will post some mini impressions (mostly versus the DX90/AK100II that I owned previously):
Boxing/Packaging
The packaging is a nice step up from the DX50/90 series. Definitely not as cheap. The included boxes for the cables and the included instruction manuals remind me a bit of the Astell and Kern boxes you get though they lack the cool branding and slightly more premium feel. Overall these are just boxes so nothing to get too crazy about. I will admit though that opening the AK100II, I couldn't help but to have a stupid smile on my face since the packaging really is premium and well thought out.
Comes with the typical iBasso stuff in the burn in cable, coaxial, and microUSB to USB cable. Also comes with two sets of screen protectors (which I already used both of since I botched the first try). The cables as usual are pretty nice in quality. No complaints here since this is mostly what you get even from the A&K units costing many times more.
Build Quality
Bit of a mixed bag here for me. I actually preferred the build quality and aesthetics of the simpler DX90. To me the rectangular shape made it look really clean and refined. Also the buttons on the DX90 I felt were more satisfying and less easy to accidentally press. This is true for the physical play/rewind/forward buttons along with the power and volume buttons on the sides. The DX90 also felt a bit more solid to me in hand.
I think the major thing is that I was expecting a unit of the size of the DX80 to have a little more heft to it. The buttons on the DX80 are definitely lighter than the DX90 so they feel a bit cheaper but nothing too bad.
The AK100II has the most satisfying tactile buttons I have ever used on a DAP. They are a nice mix of being just easy to press while still feeling solid . Also the volume wheel is pretty damn cool. The build quality is miles ahead of both players as it should be and for a player of that size (meaning it is fairly small) it has a lot of weight and heft to it.
Screen
The screen is a clear step up from the DX90. Not only it is bigger, the touchscreen is way more responsive. Though the DX90 got a bit better in responsiveness with firmware updates, I still felt that something was slightly off whenever I would try to browse through my music. This is not the case in the DX80 since it functions almost as well as a smartphone would albeit there are some minor hiccups during use which will be covered in the usability section.
The bigger screen also makes album art look way better. Not only that, they actually have the album art at nice resolution and size this time! A big big plus for the DX80.
AK100II of course has the better looking screen. Album art looks noticeably better and more colorful/vibrant. Not much more to say here.
Usability
Much much better usability on the DX80 versus the DX90. This is really no contest. The usasbility is miles ahead of the that on the DX90 largely in part to many factors which includes the larger seemingly more responsive touchscreen, the more functional GUI, and the more comfortable shape.
The touchscreen as I mentioned feels a bit more accurate than the DX90. I didn't really have to "adjust" my smartphone habits when using the DX80 as I did with the DX90. I never missed the back button or had accidental presses yet when browsing through my music which is something that happened frequently with the DX90 in the beginning. The GUI also has a better layout. You can swipe left to get to the music browsing categories (artists/albums/etc) and swipe right to get to the settings and all the major options are in nice little icons. No longer do you have to follow a tree of commands to get where you want. And lastly, while the DX80 might not have as much heft, it feels much better in hand than the blocky DX90. The DX90 to me felt a bit too wide for a unit that small and made it slightly annoying to one hand. This isn't the case with the DX80 so I like that a lot.
The AK100II definitely feels snappier and more responsive. Less lag and is as close to a smartphone experience as you can get. Even the little things about the GUI such as having a home button which lets you instantly browse artists/albums/genre makes the experience a bit better instead of having to press back a couple of times on both the DX80/90. I will admit that I thought the AK100II took a big step back with its latest firmware since they did away with the alphabet browsing. On the other hand you can still quick scroll by pulling on the slider which I used quite often when I had one.
One thing I will mention is that I have always had a hard time getting iBasso units to read microSDs and crashing during this process. The AK100II read every single type of SD card in any format no matter what which is awesome since I like to update my library quite frequently. Additionally the quality of life of having OTA (over the air) updates through wifi is amazing.
Battery Life/Memory
Battery life on the DX80 is fantastic. I hated the piss poor battery of the DX90 but hey at least it was removable. The AK100II gets pretty similar runtime for me since I use mostly MP3 files with some FLAC here and there and range from around 10-12 hours depending on how much I am using the screen. The DX90 only lasted me 8 hours at the max and usually hit around 7 hours. Awesome job iBasso with the battery on the DX80 iBasso.
Two microSD slots on the DX80 makes it better than the memory capacity on the DX90 already. And with two microSD slots, it also bests the single SD card slot of the AK100II though this unit does have a nice 64 GB of internal storage.
Sound/Tonality
Let me preface this with the fact that I no longer own all three of these players so a lot of this is from memory. Also note that I believe the differences in DAP's are very small and minor. It will take a lot of critical listen sessions to determine the differences and I don't really believe that sound quality on any of these players are that much different from one another.
The DX90 and DX80 sound different. I felt that the DX90 had a lot more energy and dynamics since the bass had a lot of weight and bloom to it and the treble was a bit forward (slight V shape). The DX80 doesn't sound as grainy and is a bit more relaxed. Treble energy is still nice and bass doesn't hit as hard. The bass has less bloom and I think that probably contributes to the "deeper bass" since you can hear more of the bass notes than before. I found myself listen to lower volumes with the DX80 than I did with the DX90 which is a nice change of pace which could be the reason why I found the DX90 to have more energy/dynamics.
As for the AK100II, I feel they sound quite similar in that they sound smooth and relaxed. The AK100II to me sounds a bit more refined and softer than the DX80. One big thing to notice was that I felt that the bass impact on the AK100II was never good enough for me even with the bassy K10's and even felt that with when cranking up the volume/applying EQ. The quality was very nice but definitely a bit too lean for my liking. I don't really feel this way about the DX80 which is awesome. I listen at lower volumes and can still rock out to EDM. Detail level on the AK100II I would say is also slightly better than the DX80 where due to the tuning of the player you could hear a bit more microdetails especially in the vocals. Definitely a more "reference' sounding player.
Conclusion
I love all three of these DAPs and think they are a great value at their pricepoint though I will admit the AK100II is much less of a value if you don't value the premium build, UI, balanced output, wifi, bluetooth and all those features. If it wasn't clear, I prefer the DX80 over the DX90 and the AK100II due to it being the child it seems of both those DAPs. It has that nice smooth sound I like with a little bit more bass with a great UI, touchscreen, battery life, and more!
For now I am very happy with the DX80 and I'm sure that it will only get better with future firmware updates. I can't believe they fit all these things on the DX80 such as having an awesome touchscreen, UI, dual microSDs, and a double DAC for such a cheap price! Kudos to iBasso for creating an awesome music player!