Just got my Q701's recently and thought I would share my opinion on them. I am using these with an optically fed Fiio Taishan DAC and a Shiit Asgard 2 amp. For anyone wondering how the Q701 + Asgard 2 work together, I will say it works fantastic. Alot of body and some warmth, not fatiguing, and very pleasant.
The higher mids and treble is absolutely outstanding on these. With these, you don't hear cymbals, you hear drumsticks striking cymbals. Does that make sense? These headphones have me excited, things like a snare drum have so much detail and information, I believe I can tell if it is a persimmon or metal snare lol. That can be hard to tell live but you get my drift.
I love the soundstage also, realistic, pretty spacey, and suspended in midair around you right out of the box without having to use software sound degrading processing to emulate soundstage.
Comparing these to my DT990s I think these have better raw sound quality in the mids and treble, but the bass is not as detailed as the DT990s, I can't quite hear the air vibrating off the bass guitar as well as I can with the DT990s. But the bass is definitely presented well as many others would say about these.
These headphones work great for things like Eric Clapton and other classic rock, blues, anything with real instruments. For things like Hip Hop they do great too, but the DT990 does better because of it's strength in the bass area.
Comfort wise, the headband does not really bother me like it does others, I kind of like the way the headband is designed as a suspension system. The clamp is a little tighter than I would like though, but I have a bigger head. I could still wear them for hours.
For the money these are a steal, but they of course need a decent amp to run properly. I was lucky enough to get an Austria model, beware that a lot of these are being made in China now.