Pros: Very detailed sound. Great soundstage. Great separation. Good build.
Cons: Light bass. Sounds a little cold. Comfort depends on head size/shape and your ears can rub against the drivers.
Comfort & Fit
The AD700X are reasonably comfortable. How comfortable they are and how well they fit depends entirely on the size and shape of your head. They are not made for something with a small head and they don't have an adjustable headband to account for different head sizes, although the 3D wings are flexible so it does have some head room (heh heh...) for fit.
The ear cups are quite large. They will fit around fairly large ears easily. The material used on the ear pads is a soft cushion like material so the ear pads are soft.
I find that after some time they can get irritating as the drivers touch the edge of my ear.
As you can see in this picture the drivers are angled so that they face more towards the back of your head when you wear them.
The material on the 3D wings is very squishy like a sponge. Because of how light the headphones are (they feel about as heavy as an iPod touch in the hand) the wings can barely be felt once you're wearing the headphones.
The clamping force of these headphones is definitely on the low side, meaning if you have a smaller head they can slide down your head. With that being said it's not too bad since they are very light.
The build quality of these is good. They're definitely not an indestructible tank but they don't feel cheap either. The two bands at the top which join each cup together feel very strong. The ear cups themselves also feel strong, and on the inside of the ear cup you can see the driver is housed within a shiny metal frame with screws and looks very solid.
The cable has adequate strain reliefs at both the jack end and where the cable joins the left ear cup. The cable itself is very rubbery and strong. Because of how rubbery it is it doesn't hold kinks easily.
The actual levers that hold the wings on feel reasonably strong.
The AD700X's are very detailed on all frequencies but light on bass. Detail retrieval, separation and soundstage of these cans makes them great for analyzing music but a lack of body, compared to a more rounded and warm headphone such as an HD558 means some may find them cold or dry for music listening.
Highs are clear and apparent and small details are easily discernible from other elements of the sound.
Mids are detailed and clear and the great separation of these cans continues here, however vocal based music is not the strong point of these headphones. While the mids are clear and apparent, these headphones do not make vocal heavy music shine. The mids are clear but lack intimacy. Vocals sound good, but not on the level of a headphone with warm and smooth sound such as HD598 or HD6xx. If you are a lover of the beautiful vocal sound that can be achieved with a smooth mid-centric headphone, you may be disappointed with the AD700X.
With that being said the mids still sound great for music that isn't heavily based around clear smooth vocals. The fantastic separation of these means that vocals are easily distinguishable from other sounds in the music and don't ever sound like they are being jumbled up with other sounds. This effect is further enhanced by the excellent sound stage of the AD700X meaning that vocals are very clearly separated from other sounds and sound like they are in a different position from the other sounds.
Bass is tight, punchy and accurate. There's not much else to say, I'm not a lover of bass personally and my opinion of the AD700X bass is that it provides a good hit and is apparent, without sounding boomy or interfering with the mids at all. These are not a bass head can but for music that doesn't require boomy bass these are perfect as they give you just enough of a bass punch to hear bass elements without affecting other frequencies and being boomy.
For the average asking price of $140 these are great value if you're looking for detailed sound with good separation and sound stage. Because of these characteristics the AD700X is also excellent for games such as CS:GO.