Which output are you having issues with? Is it a desktop amp/dac?
The J3 works fine with mic'd IEMs - no need for any adapter. So do all of my other portable players as well as the iBasso D10 and Fiio E7.
Yep, the only difference between the two variations is the color of the wood and aluminum bits and the tips. Interestingly, I think there might be minute differences between tips depending on color - or at least there are for Meelec tips which I have about a half-dozen sets of. The clear tips are a bit thicker than the black ones.