The following are my impressions following a comparison of the PK1 vs PK2, while listening to both phones amped and unamped:
The Yuin PK series of earbuds, distributed by
Head-Direct , have generated considerable interest and discussion since their arrival on the IEM/earbud scene. There have been lengthy threads posted on Head-Fi regarding these phones that one can peruse, so I will limit my comments to a brief description of the PK1 and PK2, and a comparison of the sonic similarities and differences between the two.
Both the PK1 and PK2 look virtually identical, both having a "Y" connecting cord with a straight stereo miniplug connector. These are very unremarkable-looking phones and could easily be mistaken for the low-quality buds that are usually included with various low-end players. The are both basic matte black, with thin foam pads, some of which are solid on the transducer side, and some are "donut", with a hole in the side facing the transducer.
The transducers of the both the PK1 and PK2 are of a dynamic configuration. A brief comparison of the specs between the two phones are as follows:
PK1:
Both models come nicely packaged in a sturdy plastic container that is fitted into a classy little wooden box. Included accessories included several foam covers and a 1/4" stereo adapter.
When comparing the two models, I used my iRiver H140 as an input via optical output into a Head-Direct O1-DAC amplifier. I also compared both models using the unamplified output from the iRiver headphone jack.
Both models had a similar signature, plenty of bass, very little roll-off of the highs. There were, however, considerable differences in the soundstage of the PK1 vs the PK2.
The PK1, when amplified, presented a soundstage and tonal characteristics that are very close to my Sennheiser HD650/Revelation reference phones. It was only in the very lowest of bass that the PK1 yielded to the Sennheisers! This very deep bass was apparent only on a few of the better test recordings that I used for the evaluations. The PK1 was a little more forward in the highs than the 650s, although the accuracy of the highs was surprising, considering the fact that these are earbuds rather than large phones. Even more astonishing is the level and tightness of the bass. Nothing sounded muddled or booming. Just deep, accurate, articulate bass.
The soundstage of the PK1 is wide and airy, with excellent placement of instruments and depth of field.
Dynamic range is excellent, and I was never able to hear any distortion or artifacts regardless of the volume settings. I limited volume maximums to that which I normally hear at a live classical performance out of consideration to my ears!
I needed to constantly remind myself that these are earBUDS and not an expensive IEM or large monitor headphone.
Some of the magic disappears when the PK1 is used without amplification. While it still sounds good, it does take a fairly high volume setting to yield a realistic sound level. Some of the depth and openness also is lacking when used without amplification. In all fairness to the PK1, the specifications state that an amp or high output source is needed.
The PK2 is designed to be used without amplification being required, and as such, is considerably more efficient than is the PK1. Even with low-powered, inexpensive players I was able to reach a normal listening level at with much volume potential remaining. I actually preferred the sound of the unamplified PK2 in comparison to running it amplified.
Overall, while sounding similar in tonal qualities to the PK1, the PK2 lacks the fine definition of the bass frequencies as well as lacking some of the smoothness and high-end sweetness of the amplified PK1s. The PK2 also has a soundstage that is closer to the listener than does the PK1. This is not to take anything away from the PK2, as it does a good job of meeting its design goals. There are few phones at this price that will sound more accurate when unamped.
For those who like the high-end Sennheiser sound, the PK1 will probably be very appealing, whereas those who favor the more upfront Grado sound will most likely prefer the soundstage of the PK2.
I find that I am using my PK1 for much of the critical listening I do with my desk amps, whereas the PK2 is my travelling companion when I need a small, inobtrusive carry package.
Both of these earphones are incredibly comfortable and lightweight; one soon forgets that they are even in place. It is for that reason that I find that I am using them more and more for extended listening periods.
Pros:
