I just got my used pair in today. Overall, I think they sound pretty good, and I've not heard any other AKG headphones.
The good things are that I did not find these to be too lacking in bass, which was something I was afraid might happen. I'd still prefer a bit more weight in the lower bass, but that probably comes down more to personal preference. The treble is also fairly smooth to my ears and relatively in balance with the rest of the sound. For the first few minutes, I was actually pretty happy. They sounded fairly natural overall. But, the more I listened, the more I picked up on one major flaw that annoyed me, leading to my main complaint about them.
I had noticed that measurements for the K701/K702/Q701 headphones often showed a peak around 2KHz. This was even true of a K601 measurement I've seen as well. The K702 65th AE seems to exhibit the same trait, which did not surprise me in the end. I do not find this bump to be particularly pleasant, especially for heavier music (such as Opeth at loud volume). At lower levels and/or with other types of music, it's not too bad. For how and what I most often listen to, it doesn't work out so well. I would best describe it as shouty and harsh on my ears. (I'm stealing the term "shouty" here from someone else, but I had to agree)
Using EQ to remove that bump provided for a much nicer listening experience, in my opinion. That FR bump aside, I think the headphone sounds natural, fairly neutral, and overall pretty good. I've already started experimenting with various damping materials in front of the driver to see if I couldn't smooth that bump out, and so far I think I'm making good progress (nothing new...people have experimented with that damping on other K70x headphones before). Whether I'll end up keeping them for long is tough to say.
When the price is factored in, that's where I begin to hesitate recommending these outright. It seems like these go for around $400 new and more than $300 used. I think something like the HD598 offers a smoother response at a much lower price, though you do trade for higher THD as well. I haven't heard the HD600, but I would guess that would be even better than the HD598 and more similarly priced to the 65th AE. And while the Mad Dog at $300 still isn't perfect, I think it has a more well-rounded, smoother response than the 65th AE as well. It's tuned to be darker than the 65th AE, sure, but I find that works out better for me when it comes to long and loud listening sessions. I do wish the Mad Dog's treble was as smooth as the 65th AE, but it's a smaller offense than the 2KHz bump. Don't like the Mad Dog? It's probably worth spending the extra $100 (from the 65th AE) and trying the Paradox, then.
While the K702 65th AE certainly isn't a bad headphone and sounds good for the most part, it's difficult for me to recommend them at their current price point. I simply feel there are more competitive headphones out there for the same price or less, open or closed.
Edited by hans030390 - 5/14/13 at 12:10am