Transparent, smooth sound
Hifi headphone grade sound stage
16Ohm low impedance
Comfortable traditional design, NOT in-the-ear
Ultra low distortion for high grade portable audio
PK2 earphones are the low impedance version of PK1. Although not as good as PK1, PK2's sound signature is similar to PK1. You don't have to drive PK2 with an expensive head-amp. If you are looking for something with high performance/price ratio, PK2 might be the best choice.