I've owned the clear version of the KPH30i's going on six months now.
I lost my nice trusty Yamaha studio headphones (which I used for years to mix my and other's music). I bought a pair of Sony MDR-7506 headphones, thinking they'd be the ultimate mixing headphones. I also bought these on the same day - just happened to read an article about them while researching the Sony's. They were so inexpensive, I thought why not try both?
I mixed a new song with the Sony's, thinking to myself - "oh heck yeah, I've made them sound great on the Sony's, this mix will sound great everywhere." Wrong was I! the Sony's are so bright, that I end up dulling all the instruments to compensate for the brightness of the headphones. My mixes were sounding incredibly muddy on any other set of speakers.
At first I thought the Koss KPH30i's would be too far on the other side of the spectrum - so warm, so full, so dark, so open, so transparent sounding. But I tried mixing with them any way, thinking my mix would be too bright and sibilant, and not "glued" together enough - these headphones have a way of making mixes sound incredibly "blended together" and softening transients, I thought that there'd be too much separation between instruments when translated to different speakers.
To my amazement, all my mixes with these headphones translate so well to any set of speakers. It really blows my mind. I think they really bring out the natural frequencies of recorded material, no hype whatsoever. If anything, I subconsciously try not to go "too bright" with a mix to compensate for the natural "darkness" of these phones - so the mix just comes out nice and balanced - not overly bright, not overly dark. Now I'm convinced that other headphones just bring out too much separation of different instruments (talking about you, Sony's!), even when the intended mix was supposed to be more "glued" sounding - if that makes any dang sense. I still use the Sony's for tracking, they're great for that. A metronome will pierce through any loud acoustic drum set with those things.
Been using the Koss' for months now. I pretty much make friends try them on - 100% of the time they are as blown away as I was the first time hearing music through them. They're also super comfy and light weight - you just don't get any ear fatigue, physically or mentally.
I just want to buy the world a pair of these - they're the opposite of Beats by Dre or whatever aggro sounding headphone that young people wear these days that's making them think it's a good idea to listen to people like Nick Fuentes and join the proud boys.
Sorry, long winded review. I just love these things, they've changed me!