Unfortunately, I do not have the q701 to do a direct comparison, but from what I recall and comparing with my other headphones, the k702|65 seems to have fuller bass and mids. The warmer signature sounds closer to Hd650 territory.
[EDIT] there seems to be more bass quantity than HD650.
Not sure how that extra bass is being produced, but the 65s do seem isolate ambient noise more than the q701 and hd650. Could be the new, heavier memory foam and/or combination of other materials introduced in the ear cup assembly. The foam under the ear pads look similar, but haven't opened the little back plates. I expect to find another piece of foam there. Anyone take a peek yet?
I haven't done any extensive burn-in, but the added isolation likely decreases the soundstage and possibly responsible for some perceived congestion in complex tracks. I hope that the SQ will improve over time. Whether it's just my ears adapting or the drivers - it doesn't matter. If it sounds better it is
![Headphone Smile :) :)](https://cdn.head-fi.org/e/headfi/smily_headphones1.gif)
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Another observation is the quality of HF - I think it's improved over the Q. It's been mentioned that the Q can exhibit sibilance and plasticy/artificial highs under some circumstances. Playing some of these tracks with the k702 65, sibilance seems to be well controlled and instruments like high-hats have plenty of detail and texture without smearing. Of course bad recordings will sound bad regardless.
The physical characteristics seem to be a bit more refined, too. For example, the vari-motion cups on the 65s seem really fluid in comparison to the Qs. Headband seems to slide more smoothly, too.