TL;DR Would it make sense to pair both devices with a Fiio E12 using the standard headphone jack as opposed to the Apple connector/micro USB out.    Longer version: I have a pair of HD 600's connected to the Headphone Out of my Xonar Essence STX, since 90% of my music listening happens at the...

Thank you for the information guys. @GrindingThud It's not so much a clicking but rather the artefacts you mentioned. I researched overcompression, since both of you mentioned it, and this seems to be one of my complaints with many of these songs. And the artefacts I seem to make out. 

Pretty much all my music comes from either itunes or amazon music. I've always had the feeling that certain songs have a few crackling noises here and there but because my hardware setup wasn't anywhere near hifi I always blamed it on that. A few weeks ago I bought an ASUS Xonar Essence STX and...