Hi karhujanis,
Does "more portable" mean; still in at home, but in another room ? Or while commuting/travelling ? My use case would be the first one only, and the DM13 is OK for that because even if it is a bit bulky, at home it would be fine for me. As we now have DAPs I would't consider carrying around a "discman" a some of my CDs
I can see lots of differences between headphones and some between amps, bu I'm not really able to distinguish the "sound" of various modern DAC

They are all more than good enough for me. So, with the DM13 I would easily trade "ultimate SQ" for convenience, and use the device as is, without using any other kind of DAC/AMP to improve SQ.