Review: The BIG Yuin Comparison (PK series - OK series)

[antonyfirst]

This review is my view of the so much talked Yuin earbuds: the PK1, PK2, OK1, OK2 and OK3. I want it to be a guide to give anyone looking for what earphone fits his needs better.
I'll add other AB comparisons I have done with other headphones I have been owning lately.

The earphones: PKs vs OKs
Like previously expressed by Kostalex, the OKs are slightly thicker than the PKs.
The Yuin OK series is much better looking, the earphones have metal parts, look sturdy and precious. I find the PK series a bit more comfortable when comparing them directly to the OKs. Both series are very comfortable as earbuds.

Presentation: PKs vs OKs
The OKs are a more homogeneous line compared to the PKs.
The PK1 and PK2 are very different, with the PK1 being warmer, more thumpy and midbassy than the PK2, and a lot bigger sounding.
The OK earphones share the same sound signature, while adding refinement and sound qualities to each step.
I feel the OKs start sharing a similar sound signature to the PK2, improving it.

PK2 vs OK3
I find these earphones very similar. The most noticeable difference between them is sensitivity. The OK3 are a bit less sensitive than the PK2. Using a MuVo and the OK3 I have to raise the volume of one notch to match the same volume of the PK2. It's actually a slight difference.
When I approached the PK2, I didn’t know what to expect. After reading Kostalex’ review (many months ago), I expected they sounded very similar to Koss KSC75. Furthermore, when I used to talk to Kramer about the Yuins, one year ago, I was figuring that the PK2 were “grado-like”. At that time, my only experience with a “grado” sound were the d-JAYS, which I profoundly disliked as innatural, due to the extremely nasal midrange and distorting electric guitars.
The PK2 are a lot more natural than d-JAYS. They are similar in sound signature to the Koss KSC75, but with closer soundstage and better speed. The PK2 are clearer than KSC75, especially in the bass and midrange, which sounded muffled and dirty with the Koss.
The PK2 are also more natural than the Grado SR-60, but the latter is bigger sounding and shows better instrument separation.

OK2 vs PK2 vs ER4P
The OK2 share the same sound signature as the PK2. Neither is bass heavy, but not as bass light as the ER4P (which used for constant AB with the OK2). Bass is not as deep as the ER4P, thus the OK2 might lack some impact compared to the Etys. This is partially due to the Etys being IEMs.
Midrange is similar in both PK2 and OK2. The upper midrange is slightly forward, which gives some sibilance with sharp vocalists like Freddy Mercury, but nothing dramatic, not as with the stock Super.fi 5 Pro and their spikey upper midrange, or the Etys and their “saw” frequency response.
Compared to the ER4P, the OK2 are free from the great sense of glare and “special effects” that Etys have. ER4P are artificial, they give a fake sound signature and some sickening sense to the music.
The OK2 are slightly warmer than the ER4P and don't sound empty, like Etys do. The OK2 are extremely detailed, and don't fall short to Etymotic.
I tend to like the OK2 and ER4P on the same level. The OK2 are more natural, the ER4 are more analytical and deeper. The OK2 have wider soundstage and more natural sound.

More about the OK2 vs PK2: The OK2 have more vocal clarity over the PK2.
Treble is similar on both OK2 and PK2, and not as extended as Etymotic treble. It’s more on the delicate side.
The OK2 have more defined bass over the PK2. The bass gives better sense of rhytm to the OK2.
The biggest differences between the two, anyway, come out when comparing the soundstage. The OK2 are widely out of the head, more in the same league as the PK1 and the OK1. The PK2 (as well as the OK3) are in the head and don’t give the same feeling of using a fill size headphone that the other three give.
The OK2 sound like a PK2 on steroid.

OK1 vs OK2
The OK1 sound like bettered OK2. The OK1 improve in bass presence, upper treble precision and soundstage (especially height and depth). The two have the same upper midrange response, with hints of sibilance when using very harsh recordings. The OK1 give better sense of refinement, imaging and instrument separation.
The OK1 don't fall short to the recabled Grado SR-60 in soundstage size.

PK1 vs OK1
PK1 are warmer, they have thumpier midbass, which makes for a gradoish sound compared to the neutral OK1. Vocals are fuller with the PK1, a bit less clear. The fuller vocals on the PK1 are partially due to the midbass. The OK1 have crystal clear vocals. Soundstage is wide in both cases. The PK1 have slightly wider soundstage, the OK1 have better instrument separation, which sounds more "spectacular" with the OK1 as the midbass doesn't get in the way.
The OK1 are more transparent and more "hifi", and certainly do better with classical and jazz. The PK1 sound more "effortless" with rock, thanks to the stronger midbass energy.

OK1 vs ER4P
The Etys are brighter. They have an "empty" lower midrange. The ER4 exploit the advantage of being IEMs to show deeper bass than OK1 and PK1. The ER4P have too strong upper midrange, and too much sibilance. The OK1 are not totally free from sibilance, like the RE1, but the RE1 achieved this only with recessed upper midrange.
The ER4P have more upper mids/lower treble volume, which makes for a shriller sound. The OK1 retains the same level of detail of the ER4P, but with a bit less volume in the upper mids. Thus, sibilance is less "spikey" as well.
The flatter response that OK1 have over the ER4P gives a warmer sound: vocals are very clear with both, but less sharp using the OK1. Both ER4P and OK1 have tight bass, but while the bass is "right" with the OK1, it's overwhelmed by the treble using the Etymotic.

PK1 with ER4P
I keep thinking they are equally detailed. The PK1 have more energy and fullness, especially with rock. The Etys are more glaring, ready to reveal any kind of artifacts.

OK1 vs RE1
The RE1 sound darker and more romantic, slow paced. Anyway, they miss some details that the OK1 reveal, as well as the Etys and the PK1. The OK1 are more forward than the RE1.
The RE1 have more bass quantity and depth. They seem to miss some nuances in the upper end. The upper midrange and treble are more recessed and the overall tone loses something. The OK1 scale a lot better detail-wise. Soundstage is very big with both. I like it.
The OK1 and RE1 are different flavors. I still love the RE1 and they keep being the perfect all aronder for my rock music. Treble has more volume, more "color" and nuances with the OK1, which are my favorite choice for classical. Listening to Shostakovic, the increase in details and instrument separation is very noticeable. The OK1 give a better sense of "choral" work. With classical, the RE1 sound darker when not needed. The OK1 sparkle more.

***UPDATE: OK1 vs Stax SR-003***
For this comparison I used the OK1 amped with the Headsix, and the SR-003 amped with the SRM-Xh. The Xh is a vintage amp that should be better than the stock, portable SRM-001 that comes with the portable babystax, but not as good as the SRM-252 that comes with the Stax SRS-005A package.
The Headsix pairs especially well with the OK1 with its lush, warmish but very detailed sound.
The OK1 are dry, while the SR-003 are warmer, romantic, seductive, like a sunset and a red painted sky. The SR-003 are very colored, but in a very pleasant way. I prefer the SR-003 color over grado sound signature the PK1 have. The OK1 tend to add less to the music, and to let it flow freely. Both have very good soundstage and separation, but the SR-003 are in another league compared to everything else I heard. The SR-003 are electrostatic, and that's interesting how they are very detailed with a dark sound, ie no boost in the upper mids and treble (like Etymotic do). At this point, we don't need to describe the sound signature of the OK1 any further. The SR-003, instead, have an emphasis in the midbass and lower mids. The overall tone is very pleasing, but I could use less midbass. The lower treble on the Stax is perfect, slightly subdued to control sibilance, but not muted like it is with the RE1. The Yuins can be a little brash with the harshest recordings. The stax have rolled off extremes. The OK1 have more extended highs. Both the SR-003 and the RE1 lack the deepest bass. The Stax are enveloping, seductive, romantic. The OK1 are neutral, less "fun", more analytical/uncolored.
Being the Stax more resolving they make me aware of the any kind of imperfections in the track (like artifacts). This is a downside for casual listening. These artifacts can still be noticed with the OK1, but you don't feel like you are spotting them, one by one.

I prefer the Stax (pretty much to everything I have heard), but I rate both very highly: they are so different to be complementary, and I consider them to be the two single best earphones I have tried so far (I haven't listened to the UE11).
As a guess, I think the OK1 could do really well with the Lisa III and its bass knob (so that anyone could tailor the bass at his own will), or a beautiful tube amp.
The SR-003 (or the SR-001) could do a better with Audiocats modded SRM-001 (portable amp), or with the SRM-1 MkII and the SRM-313 (home stationary amps).

Conclusion
The OK1 are very transparent and not as colored as the PK1, and for this reason they might appeal to a wider range of people. There might also be people who'll prefer the PK1, especially rock listeners and Grado lovers. Rock sounds "effortless" with the PK1. I think the PK1 color the music, which the OK1 don't. The OK1 make themselves unnoticed, while the PK1, like the Grado I have heard, tend to add the same attributes to different recordings. The PK1 are more neutral and refined than the SR-60 (see: Grado SR-60 review, in my signature).
The OK2 are very similar in sound signature to the OK1. They don't sound as big as the PK1 and the OK1, but they are close. The OK2 are a great choice for going unamped, more so than the PK1 or PK2.
The RE1 keep hitting a sweet spot for me, where Neil Young, early Pink Floyd, some Yes albums, Van Der Graaf Generator lie.

Tony

[FlavioWolff]

very good as always

[mrarroyo]

I have had an opportunity to test he PK1, PK2, OK1, OK2, as well as the RE1. My listening experience is pretty much the same as yours, however for me it was a little harder to decide which one I preffered between the PK1 and the OK1. In the end I chose the OK1 due mostly to it being a bit more musical, but it was close. I guess being older it makes certain sounds mingle and thus harder to decide amongst the various offerings.

Anyways, good job Tony.

[b0dhi]

Thanks for that comparison. Very informative indeed.

[Navyblue]

Originally Posted by antonyfirst

OK1 vs ER4P
The Etys are brighter. They have an "empty" lower midrange. The ER4 exploit the advantage of being IEMs to show deeper bass than OK1 and PK1. The ER4P have too strong upper midrange, and too much sibilance.

I find the description of ER4P very similar to what I used to experience. When the ER4P was new, it had a high mid bump that was nearly impossible to EQ it right. The low mid was also missing. And sibilance was bad. As you described, very artificial sounding.

But after 10 hours or so all those went away. The excessive high mid and treble went away, the low mid appears and gives body to the sound. Now to me the sound is very very flat and laid back, at times I even wish that there are more treble sparkle. All I can say is that it is very different now from what it was.

I know that you aren't new to ER4P, just though that it is interesting that individual experience (or may be perspective) differs.

[antonyfirst]

What tips do you use with them? I don't believe in ER4P burn in. Did you go to foam tips? They reduce the artificial feeling by a little (epsecially the Shure black foamies).

[Navyblue]

I mainly use medium Shure olives. Compared to the triple flange, I find it fuzz and smoothen the sound a bit, can be said as more natural sounding. The triple flange sounded more focused and punchy to me. The difference is there but not night and day.

I didn't believe it would burn in either. But my ear tells me either it did, or it's faulty right now. But I do miss that airy sparkle sometimes I used to hear.

Could it be clogged filter? But merely 10 hours of intentional burn in seems a little too short to clog it.

[antonyfirst]

I mostly believe in ears and mental burn in (as in getting used to a certain sound signature, little by little).

[tygger]

antonyfirst, thanks for a great review!

Did you try the canal version of OK1 too? If yes, do you agree with kostalex that it's sonically inferior to the earbud version?
Since your comparison of PK1 vs ER-4 completely conforms with my own experience I'll be definitely getting a pair of OK1 once they're available.

Thanks again.

[antonyfirst]

I tried the canal version of the OKs, but it's pretty useless in my opinion: they don't isolate and fit is almost impossible to achieve. The bass becomes stronger, but I haven't listened to this mode much. The "canal-earphones" kept falling down.