Cross-post from the other place. My thoughts align very much with
@Brooko & I'd recommend everyone read his excellent review.
I've spent a fair bit of time with the RE$2K now with the following rigs:
CI Audio VDA2+VAC1 balanced > Jotunheim > single ended
Echobox Explorer DAP
DiDiT DAC212SE
Samsung Galaxy S8
The RE$2K is 60ohm / 103dB and actually quite at home in a desktop system. They played nicely with all of the above apart from the S8, which at modest volume was fine but ran out of steam at reasonably loud levels. I wasn't able to pick up any reliable differences between the sources & I feel the RE$2K is not terribly amp fussy beyond needing a bit of juice.
Whilst some of my initial thoughts are still relevant, the Comply tips were clearly hampering things and are not a good match here, bloating the bass and upsetting the (fairly)balanced-with-a-bit-of-bass-boost sig of these iems. I rolled a few tips (tri/bi-flange, spinfits etc) and settled on
Dekoni Mercury. They're foam but not as squidgy as the Comply. Sort of a middle ground between the over-bassy Comply and leaner/brighter spinfits. As a yardstick, my favourite current headphone bass flavour is from the Eikon, and actually if it weren't for the lack of staging I'd take an Eikon as my main (with a high shelf of +2dB from 5khz).
I'll roll up my main thoughts into some bullet points (all using Dekoni tips)...
-- Slams harder than any other iem I can recall.
-- Deep sub-bass and stays tight. Passes the "Flight of the Cosmic Hippo" test
-- Modest mid-bass hump, followed by slight dip in lower mids. Subtle, works as intended.
-- A little accentuation around 5-6khz. Pretty mild, turned out not to be an issue for me.
-- Not very airy with these tips. Not dark but definitely not sparkly. Spinfits for that, but too bright for me.
-- Cymbals in Freddie Hubbard's "Red Clay" sound almost spot on, just a tad darker than realistic (again, tips).
-- Fiona Apple sounds smooth and realistic. Perhaps a fraction recessed, but no peaks a decent trade-off.
-- Stellar imaging, strong sense of space between instruments
-- Stage is wide but not very deep
-- Detail resolution is excellent. Switching between RE$2K and HD800 didn't make the former sound low-fi as often happens
-- Fit can definitely be an issue. Sharp edges not comfortable. Depends on tip depth...for my ears it's better to have the shells protruding a bit more
-- Stock cable looks pretty basic for a $2k iem. I'm not into cable-fu though, so YMMV
Ok, I appreciate I'm giving these a bl*w job here, but I really really like the RE$2K. That's saying a lot as I usually hate iems, and I've had anti-HifiMan rage in the past. Switching out with modded HD800 really shows how wonky the Sennheiser midrange is. RE$2K are getting far more head time at the moment, and not just because I'm checking them out. I was going to compare them to my Noble Savants but it took about 2 minutes to figure out that the RE$2K does pretty much everything better than the Savant (except for the cable).
BRIEF COMPARISON WITH RE800:
I also have an RE800 here, which has so far received a lot less head time. There are some obvious observations though:
-- RE800 would be pretty linear sounding if it wasn't for...
-- RE800 is brighter, peaky in the treble (7k?) and prone to sibilance
-- Sub-bass extension is there but in lower quantity. Also lacks the noticeable mid-bass hump of the RE$2K
-- RE800 is weaker on detail resolution
-- Easier fit due to different form factor
-- Captive, flimsy cable looks like an RMA waiting to happen
RE800 is for the treble-heads only imho. Still preferable to some crazy V-shaped iems out there, but sibilance is a big turn-off for me so it doesn't stand a chance.
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So, RE$2K is to my ears a winner. I've purposefully avoided commenting on the price as frankly I struggle to accept that any headphone should be priced above £1k, but clearly the market thinks otherwise so no point bleating on about it.