http://www.head-fi.org/t/822302/reviewers-wanted-world-tour-for-cayin-i5-android-based-ak4490-dap-with-wifi-dropbox-and-google-play/180#post_13012186
Some photos with 2 of my IEMs above. My initial impressions:
(1) The build is very good and the color is very good in person. Decent size screen.
(2) It is thick but not bulky. It is hefty but not heavy. It can be easily carried in the pant pocket.
(3) The user interface is decent and intuitive for anybody coming from Android world. The touch screen is very responsive. No issues there.
(4) 32 GB onboard storage and has 29GB available out of the box. Uses Android 4.4.
(5) The volume control is tight in a good way. the line out and headphone sockets are good quality. Overall the device screams premium quality.
(6) I hooked up the line out with my car stereo and it was awesome.
(7) I was using my earphones on the headphone out port and once plugged it wrongly into the line out port. My ear drums should have been blown away. But it didn't. The volume was very low and increasing the volume didn't do much. And then I realized the mistake and changed the port. On my Fiio X3 ii, i would've had my ear drums blown out by now. I don't know how Cayin prevented such a thing from happening. But I was thankful for the feature
(8) The sound signature is not reference neutral. But is very close to neutral and slightly on the warmish side. Sparkle at the top. And it extends very well in the lows. The layering and separation is quite good. Nothing extraordinary. The soundstage is average in width and it is also suitably deep. the vocals are in the center where it needs to be and then there are instruments playing to the sides and behind the vocals in another layer.
(9) The noise is pretty much non-existent and the background is black. Cayin has almost nailed the sound. And definitely they'll improve upon it in the future models (if any). But I like this sound signature very very much. all the frequencies are presented with good detail and clarity.
(10) The drums are a treat to hear on this device. Sounds very natural, has impact, texture and clarity without getting bassy. The bass is there if it's there in the song. The sound is enjoyable, addictive and pleasing. Cayin can be proud of pulling it off nicely with i5.
Drawbacks:
(1) Play by folder doesn't have the feature of playing all sub folders. If there's one, I didn't see it. In Onkyo DP-X1 and my android phones, I can easily play randomly all songs in all folders from any level I'm at. I didn't try installing a 3rd party app to see how it fared.
(2) The MacBook external Dac feature didn't work. It mightn't be a problem of this unit as AK Jr also did the same and I had to try different cables before one worked. This unit has USB Type C port and I don't have any cables to hook up to my Mac. Have to try it on windows.