Pros: intimate and sibilance-free vocals. fantastically rendered textures, sound in general
Cons: strong clamping force (pads are soft though)
So as an owner of the HE-400, I figured the 400 would be more of an update on the comfort of the model, and I was dead wrong. I find the sound signature of the 400i to be much more pleasing than the 400, but we'll get to that later. Since this is my first review, I'm gonna take the often traveled path of segmenting different portions of the review. If anyone wants pictures to accompany this, I would be happy to add them, just ask in the comments. I will be comparing the sound at times to the HE-400 with Focuspads, which do wound different than the velour pads (Better imaging, comfort, less emphasized treble, more upper mids). Most listening was done with Schiit Vali and Modi. If you don't want to read it all, there is a short summary at the end.
The packaging of the 400i really makes one feel as if they had purchased a very expensive headphone. The cardboard-ish outer sleeve comes off to reveal a leather covered box with the Hifiman logo and slogan "innovating the art of listening" on the top. Inside the box the headphones rest in a black foam cutout, with a separate cutout for the cable and 1/4" adapter. It also has that new car smell, if you really like that kind of thing :P
Outer sleeve with images (and specs on back)
Build quality for all pieces present are excellent. The cable is fabric-covered, and very flexible, with a right angle adapter. However, the cable is short (maybe just over a meter), which is nice for me since my amp sits about 2 feet away from me, this keeps me from having to circle the cable around the amp like I do with the 400. The headphones have a very solid construction, and are lighter than their predecessor. They are also a beautiful color. Artificial light makes them look like purple chrome, but when only natural light is shining on them, they look a very beautiful gray color. Props to Hifiman for making such an attractive and well built headphone.
All in the box
Headphones that look purple?
Or gray, depending on the light
Initially, I actually found these headphones slightly uncomfortable, mostly because of excessive clamping pressure, however after wearing it for a very long time (worn for about 5 hours every day 12 days ago) the clamping pressure is now just right, and they have become very comfortable. They are lighter than the HE-400, and are more comfortable for long listening sessions. Comfort for the 400 with Focuspads is actually quite good, but after being worn enough, the 400i exceeds it.
Now I'm gonna split the review up by the the usual method, then summarize my findings at the end
The usual worry for someone switching away from the 400 is whether the bass could ever be as good. Good news, I found bass on the 400i to be better. Not everyone will agree, but let me explain. The 400 has an unusually powerful wight of bass notes, but the 400i has only a tad less weight. I find it to be very close in this department. However, the ability to portray textures is beyond that of the 400, and deep bass is easier to pick up because it is less smooth than the 400's bass, in a good way. Overall I would say it is more nuanced and faster, with a similar bass weight, and more impactful, more rumbly, and what have you. If I rated the 400's bass a 9.0, the 400i's bass would be a 9.5. Not everyone agrees with this however, and I would advise looking at other's impressions as well, since other opinions are abound.
My favorite part of this headphone. The 400i has wonderfully intimate vocals, with airiness and texture again trumping the 400, and any other can that I've heard (though my experience is limited to HE-400, Sennheiser HD650, HD700, Momentums, and B&O H6). The vocals sound very realistic. The voices are not thinner and treble-based like the 400, and are a nice balance of mids and treble. I was unable to find a song that stayed vocally (or otherwise) sibilant on the 400i. I gained a new appreciation for vocal-centric music, like Birdy and Evanescence. Vocals aside, mids are nice and present, including guitars and string instruments. all around very clear and well textured, and one of the main reasons this headphone really outshines the 400. The extra mids and texture make electric guitars much more enjoyable as well.
Treble here is neutral, and doesn't do much wrong, whereas the treble was the big issue on the 400. I find the treble to be just present enough, and enjoyable. The only thing negative I have to say here is that occasionally a recording has acoustic guitars that sound just the slightest bit muted/non-resonant. Airiness in vocals is fantastic, no sibilance to be found, and all around very, very good. Lack of sibilance allows me to enjoy rap again, which is a plus as well. Treble is still present enough to enjoy with rock music (for which I find 400 and 400i about even, for different reasons)
This could be the more polarizing part of the 400i. On the 400 with focuspads, the soundstage was always very apparent at any time. With its more upfront vocals and more presence in the mids, the 400i doesn't flaunt its soundstage much. It requires a recording with intentionally distant instruments or voices to show it off. However, when these things occur, the soundstage is just a tad wider than the 400 (something I discerned after A/B with "The Angelic Welcome of Mr. Jones" by Foster the People), about equal in depth (which the focuspads increase), and a little taller. The 400i just doesn't show it off all of the time. I did find them equal in imaging, except in the case of treble based instruments, in which the 400 was more discerning of their position. Also worthy of note is the fact that before burn in or brain burn in (whatever you believe in) the vocals seemed way too upfront, to the point where it was fatiguing. After some time using and listening to them, the vocals backed off a little, but still were upfront, as I described throughout the review.
Overall, I believe this headphone trumps the 400 by a significant margin in every category except for bass and imaging. If you're skipping straight to this point, I advise you go back and at least read my input on soundstage and imaging. Bass of the 400i still has a slight edge over the 400, IMO, and I have to say that this headphone is really fantastic. The speed and texturing ability of the 400i is truly astounding. I wish I had an HE-500 to compare to, as it seems that the two were intended to be more similar than 400 and 400i. Vocal performance was what really got me, and I think there is a real sense of intimacy and realism in the vocals that I've never heard before. This is a very enticing headphone, and even though it costs more than the 400, it earns every penny of that.
Edit: I just wanted to add that this headphone doesn't have the biggest soundstage and isn't going to show every flaw in a recording, it is very musical in a still detailed and technically apt way. And as it seems I didn't mention any negatives, the closest thing I can find is that sometimes very busy passages can sound like they need more instrument separation or layering. But all in all, I really enjoy it.
P.S. ask whatever you like in the comments, I am on head-fi very often and would love to respond. If desired, I can add pictures to my review. Also, in a few days I will receive the ZMF V1 Master Model (silver rewire). If anyone would like me to compare those as well, I can do that. Thank you fellow head-fiers for your attention. Happy listening