PK2 earphones are the low impedance variation of PK1. Although not as excellent as PK1, PK2's sound signature resembles PK1. You do not need to drive PK2 with a costly head-amp. If you are trying to find something with high performance/price ratio, PK2 may be the best choice.
Hifi headphone grade sound stage
Transparent, smooth sound
Comfortable traditional design, NOT in-the-ear
Ultra low distortion for high grade portable audio
16Ohm low impedance