I had extremely high expectations for these, and they ultimately fell short. The thing is, if I did not own the Hifiman HE-400i, I think these would be a decent set of headphones (after the removal of felt mod). I don't want to draw this review out. I will just get to the point. They've had about 60 hours of break-in (maybe they need more time?). When I play them back to back on the same exact songs as the HE-400i, they simply lose all value to me. First, the clamp force is horrible. They are uncomfortable. It is a bit concerning, but you could live with it, I suppose. Now what matters... the sound. The soundstage on the 400i is noticeably wider. The imaging on the 400i is most definitely more enveloping. The 400i sounds 3D and the HD 58x, in comparison to them, frankly sounds flat out 2D. I got the 400i from Amazon for around $190. But they are truly about a $400 headphone. I believe that for a $150 set of cans, the HD58x is worth it. But if this is as close to the 660 as some say... wow. I could not imagine spending that type of money on them for the sound you get. The have hard hitting bass, and its energetic and fun. Without modding them and removing the felt against the back side of them, the bass is too heavy and can drown out some of the mids... but the bass hits hard and clean either way. I do love that about them. They sound better amped than the 400i sound unamped. I think the 400i sounds rather boring unamped. But when you give them power, my god do they come alive. The sound is just... 3D. There is a sphere of sounds, each having their own layer, around your head. You have a sense of spacial awareness. This doubles down for gaming as well. Everything sounds perfectly placed with the 400i. Then you switch back to the 58x and suddenly the music literally loses all of its magic. It is like going from a cathedral to a small room. But honestly, I do not think you would have such disappointment if these were the best headphones you had heard when you got them. For me, they are not. Each person's experience will be different. Bottom line... the HD 58x sounds like a quasi-upgraded HD 598 and nothing more: less wide soundstage, tighter and louder bass, more prominent mids and more tamed highs. All of this hype around these is now seeming to be a bit ridiculous. Sennheiser was my favorite headphone make prior to purchasing Hifimans, so I get it. Maybe everyone raving about these have not heard how good planar magnetics sound. But either way, the current cost of the 400i makes this headphone an absolute no-go unless you just need a decent set of cans that dont need an amp to get rather loud for day to day non critical listening. Sorry to disappoint, but I am honestly disappointed. These are going on eBay and my Hifiman HE-400i headphones are going back on my ears. My next set of cans will be an upgrade with Hifiman, MrSpeakers, or Audeze.
3.7/5 is my rating for these.
I cannot give them a 4, even at the price point they are at. Widen the soundstage. Get rid of all of that excess bass. Balance the sound out. They are an open pair of headphones. They should sound like it.