Hello!
Upgraded to AK70 from Cowon J3.
Thought about AK Jr for a long time. But didn't see much difference between Cowon's JetEffects and Jr. Now I see that Ak 70 really big upgrade. Sound's quality awesome for me.
I don't get battery drain, but I had really annoying little gap on the back glass, it don't fit perfectly to steel body. Somebody have the same problem?
Also little annoying for me warming during playing FLAC files.
For guys who gonna buy this device could recommend check it using something like service menu.
You should go to device menu:
"Settings" -> "System Information" and tap on "Model number" 5 times (where you see "AK70").
After this you'll see service menu where you can check base functions like Wi-Fi, Bluetooth, check different colors of display (test for dead pixels), common and balanced output and something else (I don't understand korean language).