Not only are these succeeded by the 2020 model. Hifiman already discontinued the 2020 model and released the new HE400SE international edition (not the old chinese ver) that has the same stealth magnet tech as the Susvara for $150. Is there a point in buying these over the new model anymore?
NEXONUSThe HE400i is still a great headphone, and the 150$ price is still fair. I own it, I like it and use it from time to time (as well as my HD600, HD6XX and HD58X other open headphones). Would I buy it again, sure, but now I guess I would pay a few extra dollars and try to get the Hifiman Sundara on sale instead. But that doesn’t mean the HD400i is no good, it’s just « been there, done that ». At 150$, it’s still a good buy for a very well balanced planar headphone. It’s probably still one of the best inexpensive planar headphone available, better balanced than many higher priced planars. If you are on the fence, don’t hesitate, it’s a great headphone at a great price.
NEXONUSI never actually tried HE400i but I did try HE400SE. Personally not a fan of hifiman house sound but they could've put in a little more budget for the HE400SE cable. The stock cables from the HE400SE is just so bad.
I have wires that look and feel very similar to the HE400SE cable and they were like $1/m. Probably can get them for like a few cents a meter in bulk.
NEXONUSI just feel that it's quite troublesome to have to change cable just because they cheap out on the stock cable. Best of luck finding something to replace. Unless you can tolerate using that cable.
NEXONUSThe 4ft supplied cable on the HE400i was too short. I bought an aftermarket cable on Amazon, 9ft from New Neomusica, but it is good and was cheap to buy, around 20$ if I recall. It’s far better than the supplied cable.
NEXONUSJust in case anyone else is wondering about this question, I have tried the HE400se, He400i (both 2016 and 2020 versions), and the HE4XX, as well as many Hifiman headphones all the way up the chain, and aside from the OG HE400, the 2016 HE400is are my favorites from the HE400 series. The 400se is a much drier sounding headphone that comes across as a bit more neutral in comparison. The 4XX is a warmer sounding headphone that sounds a bit veiled and seems tonlose some of the detail especially through the mids. The 2020 version of the HE400i sounds nearly identical to the 2016 with some very minor differences that are so small that they aren't even audible on many tracks, but they are significantly less comfortable than the 2016 version with the suspension headband. I also think the HE400i scales with better signal chains to a greater extent than the HE400se, though I can't comment on how the HE4XX scales because I didn't get as much time with varied gear when I had them around.
If I was looking to purchase an HE400 headphone today and wasn't willing to pickup a used OG HE400, then I would definitely buy my 2016 HE400is all over again without a doubt. I actually like them quite a bit more than the HE5XX. That said, with versions if the HE560 and the Sundaras available for under $300 brand new these days, it makes sense to start with them *if* your budget allows (I prefer the HE560s and find the Sundaras a bit too bright, but that's for another post). The 2016 HE400is are still a very relevant headphone in today's market and they're a great, exceptionally comfortable budget planar.
***Disclaimer: All of this is just my opinion based on my experiences and, as with anything in audio and head gear, YMMV.