Well the Q40 do sound balanced despite being basshead material and very clearly so, the mids and highs are just unusually even and neutral despite the bass is boosted severly. There's a slight peak around 8~10kHz area which tames down with burn-in but I stuffed a piece of paper roll underneath the pads which have holes in them on the underside and bringing the drivers further apart from the ears and covering the holes seems to tame down the peak ever so slightly and possibly increase the soundstage a little as well.
Like so
compare to stock:
They are closed (the grille at the back is mostly for asthetics) but I opened them up and saw it actually has a few very tiny holes left open at the back of the cup (invisible from the outside) in 4 places of the cup (the corners). It still has quite decent isolation though but not excellent (but without these holes the soundstage would probably suck).
I've been thinking whether I should remove the foam ring in the middle surrounding the driver though but since I've been so pleased with the sound anyway I haven't dared to do it in case I'd regret it. It's just I'm thinking the soundstage might be further improved by removing this ring.
These have like previous person very well extended, textured, accurate but strong bass response but are at same time very detailed. Mine has held up great so far and I hope they continue to do so, I've heard the cable is what usually breaks easily but haven't heard much about the drivers themselves dying. I thought the included cable is actually quite good, typical studio headphone cable that is quite thick but yea since it's removable and it's using standard sized 3.5mm headphone jacks on the both ends u can easily buy your own stereo cable for it.
These are my clear favorites so far as they do great in the whole frequency response range (boosted bass + neutral mids & highs). I paid 99 EUR for mine, they usually go for $120 streetprice lowest in US. Sound wise comparing between all headphones I've tried they are easily worth to me at least ~$150 stock without any mods or EQing. They do like some amping to get the most out of the bass response especially, they seem to become more dynamic and fun sounding with a little amping to it. Together with ZO2 amp makes me smile whenever I put any bassy hardstyle song on, it just sounds like it's supposed to, like listening to a pair of KRK monitor speakers which are popular among hardstyle producers. I can wear them for hrs and hrs without any issues regarding comfort (beware they do clamp above average at first but despite so it's not uncomfortable to me at least) or sweat and they are also quite lightweight despite being quite huge in size (they look bigger in real life than on the photos).