I use PK1's with a PORTA CORDA 3 MEIER amp. The PK1 is just so detailed, so clear, with an amazing
soundstage, that from the start I had the rare feeling (for me) of not even being curious about any other
in-ear headphones. I'm speaking from a quite limited, narrow experience with ear buds or any other in-ear
models, just some crappy ones and PK1,but I just don't see how anyone could go wrong with these.
And customer service at YUIN has been the best.