iBasso DX50 => breath because of the low impedance of FA4, but very good SQ
Fiio X3 => little aggressive especially in high mid and not as 3D and fluid than on DX50
iPhone 4S => essentiel of FA4 is here, but not as spacious as with a good amp => iPod Classic + RSA Hornet : whaou but not very usefull / iPod Classic + Pico Slim : more precise, less big and deep, but very speed.
The build quality is not so bad, pretty good in fact, but it's made by a 3D acrylic printer, also not as good as a real custom ;-/
Edited by Rollk2 - 11/29/13 at 7:17am