I got my pair super quick. Here are my first impressions:
I love the color. I got crimson red and it's a bit darker red than it looks in their picture which I'm really happy about. The coating makes it a bit more reflective and less speckly unless you get really close. Very nice looking. I've attached a pic that's more accurate below.
As for size, it's pretty low-profile and stays in that area of the ear as opposed to protruding out like my ATH-IM70. However, it's just a little too long going back and it presses up against my ear. I'll have to see if that causes any discomfort when worn for a long period. The seam between the two halves of the casing is very smooth on the left one except the back whereas it's much more pronounced and can be felt as an edge on the right one. It also looks like a small part of it got chipped under the coating.
I am not a fan of the cable. I like how it uses a 45 degree angle and it has a nice strain relief. However, the slide to keep the two earphones together is so tight that you have to use so much force that I worry that I'll damage the cable. Also, at the top it isn't memory wire as I'm used to. You can't really change the shape of it. It just stays how it was made. No bending it to your ears. And the tubing isn't long enough. It's the exact length for the edge to touch my ear, causing the relatively sharp edge to rub against it. Also, I like how thick the one on my IM70s is because it keeps it pretty tangle-free. This one is thin so it tangles very easily. If the mic + remote cable is like this I might have to get the expensive UE one.
The nozzles are little small for the SpinFit CP100 tips. They go on and don't come off in my ear, they're just a little looser than they would have to be for me to be totally comfortable.
The sound is really good. Keep in mind I'm not an experienced audiophile and I don't go in for all the jargon. I tested them with a Pixel XL, Pixel 2 XL, iPad Pro, and my PC (gaming motherboard with isolated sound card through a keyboard) and I don't think I heard any significant difference. Didn't have to turn the volume up very high on any. Compared to my ATH-IM70, they are clearer, have a somewhat larger sound stage, and I think a bit less V-shaped with a bit less bass, though better defined bass like the rest. The sound signature isn't too different which I'm very happy about. The unnatural vocals I heard on the ATH-IM02 are not found here. I can breathe a sigh of relief. Not a monumental leap over the IM70 but definitely an upgrade that pleases me. I am hearing things I didn't before in my songs, that when I go back and listen with the IM70, they're present but not as defined, separated, and enjoyable.
The accessories are nice. Extra tips, Comply tips and cleaning tools are very welcome and the case is nice and sturdy. A lot of IEMs come with stupidly big cases. This one's not too big, though I'd prefer it to be like half the size as I don't need to be carrying the accessories around with me and if it was thinner you might be able to get it in a jeans pocket.
I just typed in a rather lengthy reply about some of the differences, but when I pressed "Post Reply", it didn't show up even though the beginning of my reply can be seen on my profile under "Recent Posts". To make it short, what I wrote was basically that the B200 is more laid-back between 3 and 5 kHz, whereas the B400 is more in the background around 11 kHz. No major difference on the technical side, just some things the B400 does a little better in direct comparison. The B400 has got a softer treble compared to the B200 despite being less laid-back, giving it what some people would probably refer to as "analogue" sound.
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