Pros: Overall bass presence and impact, detail and texture of midrange, sweetness of treble, isolation, overall comfort, natural sound and balance
Cons: Bass and treble extension, comfort for those with very large ears, mic in a terrible place
First impressions is these is they are very nice in person. They're light for full-size closed cans and the cushions on the earpads and headband are very soft and comfortable. The cups themselves are plenty big to be circumaural for almost everyone but they are a touch shallow, so big-eared folks like me either need to get used to a little ear-to-baffle contact or get new pads (I hear the SRH-840 pads are a good fit). Isolation is great, better than most closed-back headphones I've tried. The cord on this particular model has a L-shaped jack and an inline mic higher up on the cord than I was expecting. The mic placement used to bother me because it would catch on the top of my jacket as I walked or turned my head, but now that I've started putting my jacket over my headphones, I think it's perfectly placed. The mic and control peek out the top of a closed and zipped jacket, as opposed to a more conventional design which forces you put the cord on top of your jacket to use the mic. I think the cord is just right for portable headphones. The length is perfect for everyday use and use at the office, the l-shape of the jack makes the jack-cord connection really secure and safe for your expensive DAP's audio jack. I'm using an HTC One S as my primary source for these cans and it does a great job. I didn't notice any difference between my sound card and the phone, and even the performance out of the built-in audio jack of my work machine was close to the phone's performance. These cans are really easy to drive well. The majority of my music collection is 320kbps and FLAC with some lower quality files thrown in. These cans will treat a good recording very well, but is also kind to the crappier quality files. I don't regret shoving FLAC onto my phone when listening to these headphones, but I don't regret bringing along lower quality files either. The zx700/zx701ip scales well, but still manages to be forgiving of poor quality files.
ON TO SQ!!
Bass: Overall, above neutral as far as response. Impact and weight are very good, and detail/texture are even better. It doesn't extend down very far unfortunately. For most music, the bass is more than adequate. Only in the deepest dubstep drops do I really hear any significant roll-off (below that point it's pretty obvious). For reference, on a 4 string bass guitar tuned to drop D, the bottom string played open (36.71Hz) sounds in line with other notes. Below that there be trouble for bassheads. But for normal folk, it should be more than fine. If I were to nitpick, I wish the bass had a little more immediacy (especially at lower volumes), but the urgency is competent enough to keep me satisfied on most metal tracks (more than plenty urgent for Tool).
Midrange: This is the strength of these cans. The mids are a little forward compared to the lows and highs, but more importantly the quality of the midrange is spectacular for the price and design. Without a doubt, some of the best mids I've heard at this price range. It's warm, weighty, textured, detailed, sweet, but above all else very natural, especially for a closed-back design. Vocals are spot on (both male and female vocals are handled very well), and guitars are delicate yet substantial. People have remarked that acoustic guitars are a particular strength of these headphones and I would agree, but I must mention the way they reproduce electric guitar is lovely as well. It's the substance behind the midrange that impressed me most about these headphones. The way that buttery-warm substance plays with the delicacy and detail is borderline magical (a word I tend to save for Grados). These headphones make music "pretty" in a way that few other sub $200 headphones (none closed-back) can match. Overall, a very musical, warm, natural midrange.
Treble: Compared to the midrange, the treble is unremarkable. That's not necessarily a bad thing, as one of the main aspects of the zx701 (zx700) treble is it's lack of shortcomings. It simply doesn't do anything wrong, though it's not the standout performer that the midrange is. Cymbal crashes are nice and natural, if a little tiny bit distant. Sibilance is non-existent, no matter how hard I push it. Overall it's nice, smooth, detailed and pleasant. It will sparkle and shimmer if the recording calls for it, and there's good air and lightness to the overall sound, there's just no WOW factor. I also feel like it doesn't extend upwards like its specs say it should (5-40,000Hz seems like marketing BS to me).
Compared to the sr-80i: The Grados are open backed 'phones, so a pair of Grados is a completely different beast, but given the similarities in price I thought I might attempt an apples to apple-shaped oranges comparison. I won't go into the obvious functional differences, other than to say I used my Grados on the bus every day for 3 months and am very glad to have the Sonys for that job now. With respect to sound quality, the Grados have some distinct advantages. That "pretty" midrange effect that the zx701-zx700 has is even more present in the Grados. SO PRETTY. The bass response is quicker (and since I'm using taped bowls, the impact is comparable) and the treble is much sparklier. The Sonys are very deft and agile sounding for a closed can, but the Grados are agile, period. They also have this energy that the Sonys can't quite match. On the other hand, the Sonys have a warmth and substance behind the sound that is missing from the Grados. Overall, I'd say the zx700-zx701 provides a much better portable listening experience, but at home the Grados get the nod.
Compared to the srh-440: The Shures are absolute detail monsters, technically proficient to a fault. And in comparison to the Sonys, that's where they fall short. The shures are too focused on being good monitoring headphones to be any fun at all. The treble sparkles more on the Shures, but it reveals any harshness that might exist (and I mean ANY harshness) on the recordings, making some of my favorite tracks borderline unlistenable with all that extra 'tsss-tsss' of cymbals. They're also very cold in comparison to the Sonys. The naturalness, prettiness and musicality that defines the Sonys is almost completely absent in the Shures. Bass response is roughly equal between the two, with the Shures getting points for slightly better extension and the Sonys getting them back for better warmth and texture. My recommendation would depend on your purpose. If you're making music, you should get the Shures as they will highlight mistakes and tear poorly mastered tracks to shreds, but if you're looking to enjoy music, you should get the Sonys.
Compared to the Phillips Uptown: I wish I could give a more detailed comparison, but I returned the Philips a few months ago due to me hating them (so no AB, sorry). The Philips is more stylish IMO and has a very solid premium feel. This made them kind of heavy, but the comfort was great regardless. The sound is why I'm keeping the Sonys as my daily driver and the Philips went back. I remember the Philips being thin and hollow sounding compared to what I was looking for. I love and was immediately impressed with the texture, warmth and depth of sound the Sonys give me FWIW.