A great pair of headphones for the money.
Very comfortable headphones for people with giant noggins (after a few modifications). Very good imaging, separation, and soundstage, especially in this price range. Pleasing tonal balance after a pad swap. I like them more than the HD6XX or HD58X.
I bought these as an upgrade to a pair of AKG K240 studios. I own a few pairs of headphones that are "nicer" than the K240s, including the MrSpeakers Aeon Flow, Audioquest Nightowl Carbon, and HiFiMAN He-400i, but the K240s are my daily drivers for work because they're SO much lighter than the others and have the least clamping force, so I can wear them the longest without getting a headache. Why is this all so much of an issue? My head is enormous. I can't even wear adjustable, one-size-fits-all baseball hats. They just sit on top of my head like a thimble on an orange.
I've replaced the earpads on the K240s with a softer pair than what comes standard, and I've cut the elastic on my 240s because other wise they didn't sit far enough down on my head without putting a lot of pressure on the top of my head, but with the elastic cut, they're extremely comfortable. My hypothesis regarding the K7XXs was that they would be ergonomically and sonically superior to the 240s.
I have a large head, and I use headphones for multiple hours every day. That usually poses me with some ergonomic challenges. The K7XX is the lightest "audiophile" headphones I've encountered, and their ear cups are very spacious. My ears don't touch the insides of the cups at all, which I appreciate. The 240s are almost more like on-ear headphones, so the biggest comfort issue with them is my ears beginning to feel compressed after a few hours.
I've replaced the earpads on the K7XX with Dekoni Protein Leather earpads because, although the velour pads that come standard have a nice texture, the foam is far too firm. It doesn't conform to the contours of my head to create a good seal. It just cuts into my head, creating pressure points and hot spots that distract from the enjoyment of my music. The Dekonis are vastly more comfortable. I have the same issue with the HD6XX velour pads. They're like velour-covered cement.
I've always found suspension headbands more comfortable than regular headbands. Unfortunately, the headband on the K7XX doesn't really extend far enough down for me to get it to center around my ears properly without it resulting in the headband exerting a great deal of pressure on the top of my head, an issue my K240s don't have. There are a couple of plastic pieces that brace the suspension system but that impede the vertical extension of the K7XX's headstrap a centimeter or so lower than I'd like.
Oh, and the K7XX is LIGHT. It's SO light. I'm completely in love with how light it is. It's the lightest full-size headphone I own. It's even lighter than the K240 which feels like it's made of papier-mâché.
I erroneously assumed that the K7XX would be more generously proportioned than the K240, but it isn't, vertically speaking. The headstrap on the K240 is also deeper front-to-back, so it disperses the pressure along a larger area of my head, creating a greater sense of invisibility. However, I am going to try to modify the K7XX headband to make it extend further without putting so much pressure on my head. I've never once owned a pair of headphones that didn't require some modification to be comfortable. Not even my Aeons and Owls, both widely lauded as being two of the most comfortable headphone designs in existence, didn't escape a touch of modification just to make them that little bit more comfortable. Like I said, my head is HUGE. I do feel compelled to modify them to make them more comfortable though. Why?...
The K7XX sounds very good. My pairs from MrSpeakers and Audioquest are overall more resolving than the K7XX, but the K7XX frankly has a much larger soundstage and images better. And although the Nightowl and Aeon do feature good senses of separation, the wider stage of the K7XX allows for a great sense of separation.
A big part of my enjoyment of music is dependent on my ability really drill down into the music and hear the different parts of what's going on, and the huge stage and excellent separation of the K7XX really facilitates that to a delicious extent. Even though the Aeons are more resolving and faster, some fun musical details shine through in the mix more with the K7XX just because of their great separation. The sound signature of the K7XX with the standard velour pads is a little shouty and lean, with the bass laying back a touch and the upper mids being a touch sharp. When I switched the velours out for the Dekoni pads, the bass become richer and fuller, and the upper mids chilled out a little, resulting in a much more pleasant and balanced overall tuning.
I don't mind lean bass if it still feels appropriate to the music, but I can't listen to sharp upper mids or highs very long without getting fatigued, which is my biggest issue with the K240s. They have very lean bass, again not a HUGE issue but still not ideal, but they have some peaks in the presence region that wear my ears out, so I have to listen to them just a little quieter than I'd like in order to be able to use them for extended periods. The K7XXs with the Dekoni pads do not have this issue. They are very nicely balanced, are more resolving, have a wider soundstage, and image better than the K240s. Total slam dunk. The K7XX is going to be a great daily driver for use at work (I sit far enough away from anyone else that nobody will hear my music, even at medium volumes from an open-backed headphone).
Selected comparisons of other phones in the general price vicinity:
HD6XX (have listened to extensively due to multiple friends owning them): I prefer the K7XX to the HD6XX. I know this is a minority opinion. But I find that with the Dekoni pads, the K7XX has a fairly similar tonal balance to the HD6XX but with MASSIVELY wider soundstaging and superior imaging and separation, which I think are really the magic ingredient in truly great headphones. As much as I think Sennheiser is awesome, those 600 series phones have, to my ear, pretty mediocre soundstage, imaging, and separation, which makes them just a little underwhelming for my taste. I also really don't like the ergonomics of the 600 series Senns. I find them endlessly uncomfortable. I'm sure this opinion here isn't all that helpful to most though. The 600s are nearly universally beloved for a reason, I'm sure. They just don't hit me the way they hit everyone else, clearly.
HD58X (I own): Pretty much the same story as the 6XX but with a different tonal balance and with a driver that's easier to drive. All the same notes regarding soundstage, imaging, separation, and comfort.
HE-400i (I own): This one's a little trickier for me. I find the 400i much more comfortable than the 600 series Senns, but they have a lot of the same ergonomic challenges that the K7XX has. The HiFiMAN phones come with much comfier pads, but they don't extend vertically as much as I'd like. I've dismantled them and inverted the headstrap so that it can extend further up. That's helped quite a bit. The 400i might be a touch more resolving than the K7XX, and it is faster, but it's also a little grainy in the mids and treble, the K7XX not so much. The 400i is much heavier than the K7XX though, and the K7XX, like with so many others, handily bests the 400i on imaging, soundstage, and separation.
Would recommend to a friend.