Hi Guys,
I thought I would try to contribute a little bit to this community, as all I have really done so far is read. Hifiman is a bit of a controversial brand. Be it poor build quality, insane top of the line pricing, or the materials they use. I had sworn off Hifiman for good after a poor experience with the HE1000V1 build quality wise, but as it happens, I now own both the RE2000, and the Sundara. I also owned the Susvara for a while, but had to sell them sadly.
Anyhow, I’d like to post about the RE2000 because I am smitten with them. They are my favourite in ears yet. If I only focus on the sound quality, not the build, or price, they are really good. Well, at least to my ears they are. The RE2000 now comes in at $1500USD MSRP for the silver version, which is a bit better than the ridiculous $2000 for the gold version. I reckon if you do a bit shopping around and ask nicely, the silver version will be able to be had for around the price of the CA Atlas, or even the Andromeda. With all that being said, I still think the RE2000 are too expensive.
Heres the rub. I prefer the RE2000 to the Atlas, and the Atlas is a really superb IEM. The RE2000 has less steely treble, a bit more balance in the low end, and smoother mids. In terms of sound signature and technicalities, they are indeed pretty close to each other, but I do find the RE2000 is more to my taste.
The bass of the RE2000 is just about right for my ears. I like to bring it up via EQ a couple DB, but that is personal preference and I reckon that for most listeners, it will be just fine in the stock tuning. The bass is less round sounding than the Atlas, and a bit less boomy. It sounds tighter, and has more attack.
The mids are smoother than the Atlas, and a bit more present in the mix. Vocals are presented really well. Thats not to say the RE2000 are a warm earphone, they aren’t, but they do mids well. I like a bit of a V shape in terms of sound signature, especially with earphones.
The treble of the RE2000 is less sibilant than the Atlas. In fact, unless you are really blasting them, there isn’t any real noticeable sibilance. As I said before, the RE2000 seems to have a less “steely” or metallic sounding treble than the Atlas. The treble is a bit raspy sounding on the RE2000 though. I think it will really depend on the listener as to which they would prefer between the Atlas and RE2000.
In terms of soundstage, the RE2000 is more to my preference vs. The Atlas. It is wider, and has a more spacious sound. There is an airy quality to the treble I really enjoy. The Atlas are a fuller sounding earphone however, perhaps due to their increased bass. Detail is pretty much a toss up between the two, with the Atlas having the edge in the bass, and the RE2000 having the edge in the mids and treble.
One thing I was really worried about with the RE2000 was the build quality and materials. The build quality is better than I thought it would be, but it just isn’t….perfect yet. Similar to the Susvara, they lack that last 5% of attention to detail that would really make them stand out. The Atlas beat the RE2000 in every way shape and form in terms of build. The included cable with the RE2000 is a joke. I changed it out pretty quickly. In terms of comfort the RE2000 is ok, its not terrible. I have used more comfortable earphones however. If you have small ears, you might run into some fit issues with the RE2000, so I would definitely recommend giving them a try (if you can) before purchasing a pair.
They aren’t an easy to drive earphone, compared to some others. They are ok out of an iPhone, but not great. I’m not saying a fat amp is necessary, as I just used them on a 9 hour flight out of my iPhone, but they do sound better out of something like the Chord Mojo.
All in all, these earphones are a bit of a conundrum. They sound, to my ears, epic, but they lack the finesse in terms of materials and build quality that something like the CA Atlas has. They are also too expensive at their MSRP. I got my pair for a lot less than MSRP, which was lucky. Anyhow, if you get the chance give them a listen, I think you might be pleasantly surprised 
But with that being said I have had a few IEMs over time. I think for their current sale price they hold up well against other TOTL IEMs I have heard.