Great review!!
Funny that when amped, I find the bass of the porta pro not fatigue-free in some tracks.

@LordZero Thanks! Weird indeed, about the porta pro. I do have a lot of power with my Ibasso DX160 but it was still fatigue free for me, due to its low treble quantity.

Try some yaxis on the porta pro, it really tames the bass if it's too much for you ootb, it also lifts the mids and treble noticeably. Though, with the 75s I like the stock pads enough. If ever someone is pressed on cash and still wants to enjoy good SQ, these 2 Koss can be really endgame material in terms of portability, price and SQ. I feel like everyone who's just starting in this hobby should get these first, as they will clearly give you an idea how the diminishing return works in this hobby.

@1Q84 they are quite expensive for me to get with shipping and import fees. I got the Sony mdr-1am2 for a bassy set, so no need for me to upgrade the Porta pro.

Excellent review!