Tldr – The best budget full-sized neutral headphone that you might not like.
The gist – Standard neutral with a little bit of warmth, sometimes almost dry in fact. Almost linear response and some sparkle in the highs but also has a peak at around 2k.
While not nightclub level, the K612 can pump some bass when the song asks for it. Appropriate servings of bass that is. If you want a whole cow serving of bass, EQ is your friend. Decent detail retrieval. This is more than enough to make me happy.
Mids are all right. While not getting the same detail retrieval as its bigger brothers (K702, K712), it sounds quite decent. Since it’s a little bit more intimate compared to its bigger brothers it actually sounds more natural. Then there’s the 2k peak.
I actually don’t notice the 2k peak that much but since every review of the K612 mentions it I guess I have to mention it too. I think it’s doing some kind of “fake detail” by elevating 2k.
Also every now and again there will be a cymbal that sounds off, yup that basically all I got. Rest of the highs are fine though, never tiring. I will say as a disclaimer I lived with the Superlux HD 681 for a while and it took me a while to notice the ice picks going in my ears, I might have accidentally gained/found a super power.
The best way to put it is that I wouldn’t call this headphone bright but if someone does, I’d agree with them. Odd headphone, huh?
I think the soundstage width/depth is the average open back width/depth, natural and never too wide, with good imaging.
Everyone recommends using an amp with these to give it enough power and I agree. I find that my Xduoo XD-05 does fine powering it but because of driver issues with my PC, I just plug mine straight into the mainboard audio jack. Not a huge difference but there is one and it’s fine with normal use (videos, games, occasional song) but if I’m going to have a listening session, I have to plug it into an amp.
Super comfy and super light. I can wear this for hours on end, and I wear glasses with these.
While the cable is super soft, I think it would have been better if it was detachable.
All this makes the K612 sound boring as hell, and it probably is. I mean, it is called “AKG K612 PRO REFERENCE CLASS HEADPHONES” I don’t see the word “FUN” or “BASS CANNON” anywhere in that string. Why I love my pair is because it’s actually somewhat neutral. I think it’s the best neutral headphone at it’s price range despite lacking detail retrieval compared to say, HD600 or DT880. And a 2nd hand K612 being sold at a bargain is the best way to introduce someone to actual-good-sounding-not-bass-rape-mids-scooped-out headphones