Right now I have a pile of earphones sitting on my desk as I very slowly and not so diligently amass a big review for all of them. (thread elsewhere but not important till I actually finish it up) I've used a number of other earphones along with the RE-252 in the past as well.
These are the earphones I've owned/borrowed while also owning the RE-252:
Audio Technica CK10
Audio Technica CK90Pro
Audio Technica ATH-CK100
Head Direct RE-ZERO
Head Direct RE-252
Head Direct RE-262
Klipsch Custom 3
Sleek Audio SA6
Ultimate Ears Triple.Fi 10
Typically I focus on a certain series of aspects when I review and evaluate earphones. There are certain qualities I expect from a good earphone like balance, a well defined note, good transparency, high clarity and low distortion, good presentation of sound stage, etc. There have been a lot of earphones I've liked over the years and many I very much value as good products. At the end of the day, I feel the RE-252 beats them all.
First, it's one of the most balanced earphones on the market. The frequency response is basically flat and very extended on both ends, better than most other products on the market. But it's not just frequency response. The intensity and presence of the note is even throughout. Bass doesn't lean out or weaken (does need a good seal) and the highs don't soften nor smooth out. It's just even, everywhere. The balance doesn't stop there. Dynamics are well balanced, texturing is natural, and the resulting sound stage and sense of space is decently natural and linear.
What about accuracy and speed, not clarity, distortion? I mean balance isn't everything, right?
Yes, balance only gets you so far. You can still end up with a muddy sounding earphone despite being well balanced. The driver(s) still have to be good. They need to be fast, accurate, articulate, and distortion free. Again the RE-252 wins here. The driver is incredibly fast and effortlessly so, even versus BA based earphones. There's got to be faster earphones though. Yes but only a few. The CK10 is one. That earphone is just nutty fast. The newer sibling RE-262 is too. Point is, the list is very short. The RE-252 doesn't suffer from an overly short note and retains excellent body and texture. Sound is effortless and full. Dynamics are broad offering excellent subtlety and believable power. Distortion is also incredibly low which allows for very high transparency. All of this mixed allows for a very resolving and better yet very believable earphone.
There's got to be some bad things about the RE-252. It's not all unicorns and rainbows.
No, it isn't. There are always shortcomings of one sort or another. Must of it revolves around the physical design. Many of you already know about the gummy structure that fits in the ear space. It's sort of a one size fits all thing which means it doesn't fit all. The best advice I can give is to own a lot of tips. Comply foams are the end game fix, but open cell foam will soak up some top end as well as soften bass impact. The cord isn't anything special but not bad in any major way short the lack of strain reliefs. It's exactly the same as the RE-ZERO cord. It's not bad with microphonics but anything not over the ear has some.
Wait. There's got to be some bad things about the sound too, right?
Yes, a few. First, the dynamics are not limitless. This earphones has amazing subtlety, does it better than most. Dynamic range is pretty natural, but it is noticeably constrained at higher volumes and tends to compress more the higher you go. I'm not sure if it's a lack of motor strength, high loss damping, or what. It's something that got fixed with the RE-262 because the RE-262 is absolutely effortless to very loud. The RE-252 is better suited to quiet to medium volume listening. It doesn't scale linearly above that. Isolation is good though, so there is seldom need to really crank these. They don't sound bad turned up. It's just that there's dynamic compression when you do that's a byproduct of some part of its design. The enclosure gets noisy too and retracts from the transparency and sound stage depth at these loud volumes too, I will state that these changes are mild.
For all the good and bad about these, why should I consider these over something else?
Plain and simple they are most balanced and accurate across all genres compared to most everything else out there. Many of the other high end earphones are moderately colored, great in certain ways, but comprehensively less balanced. The RE-252 do so many things so well yet has very few shortcomings. The driver is effortless quick and detailed rivaling what you could find in even a BA based earphone. The clarity, speed, and cleaniless of this earphone allows it to separate and individualize complex layers of information better than most. Notes are well-bodied and impactful. Notes carry energy and a real sense of power, not uncommon for high end earphones, but it does it through the entire spectrum which is less common. They're comprehensively better than most everything else on the market remotely close to their price point or otherwise for that matter. They're just $200 new and often around just $140 used which makes them a top tier product at a mid level price point and a killer buy.
Well if the RE-252 is so good, why not buy the RE-262 instead?
Well first of all, they are yet to be sold. The only ones in existence are from the HM-602 pre-orders and that's it. Second, the RE-262 isn't as balanced as the RE-252. The frequency response is actually only within a couple dB of each other, but the presentation is different. The RE-262 notes are lean which does carry less presence (bad), more dynamic and effortlessly so (good), and is more transparent (good) but has a lesser sense of space due to the leaner note (bad). What about the physical. Well, the RE-262 is easier to fit in the ear with no gummy structure. I do like the improved holding power the gummy adds though and it can be trimmed, sanded, melted, completely removed, etc. if need be to actually get the fit better. The cord is slightly thicker with the RE-262 with a slightly stiffer casing but still nearly identical to the RE-252 and RE-ZERO. Basically it's a mix of things, and the RE-252 just offers a little more range and balance and the heartier note does make for a slightly more believable presence. Really, they're pretty much on par with each other, and it's just a series of trade-offs, but I feel the RE-252's trade-offs are more acceptable.
What might you not like?
The fit. It really does take a couple weeks getting used to. The stock tips are very limited and not exactly great. I advise ordering some extra tips to find something that you'll like. A suggestion:
But you could also decore a set of Shure foam tips which are closed cell and doesn't have the coloration issue or grab a Comply T-500 set for maximum comfort (can grab a s/m/l set if you want to experiment), but I like the combo pack idea, and the Monster tips are well liked and function well, plus something like that offers a LOT of options to try. The challenge is trying to fit the tip AND the gummy in two separate areas and you want to end up with a solid seal or you lose all the bass. Outside of fitment, these earphones are not terribly forgiving. If the recording quality is bad, these earphones will sound equally bad. These are very detailed, very revealing earphones and they can sound amazing or sound like cheap crap depending on what you feed them.
Why did I bring up this thread at all in the first place?
Simple. I think the RE-252 is probably one of the most overlooked top level earphones on the market. It has really been the only other earphone I've used that I view like the ER4S and respect as much for being a true reference level product. I think too many people overlook it fearing the issue of fitment or being underly flashy or whatever, but really, there are work-arounds for everything if sound is your true end goal. If sound is all that matters, this is one of the best in my opinion, for whatever that's worth, oh and it's cheap as dirt, so there's that too. Don't be disappointed that this really wasn't a review. I wasn't intending to review this earphone since I already have reviewed and commented elsewhere several times. This is more of a tool to spark some interest in a product worth looking into because I really do feel it's absolutely one of the most balanced and most accurate IEMs on the market and the new/used pricing pretty much puts it in just about everyone's reach.