Pretty much all of my audio products are Sennheiser. I love their headphones but I do own a pair of CX-300 earphones and well... the sound is good but they basically started to disintegrate a few WEEKS after I bought them. And yes I took very good care of them. I recently gave up on mobile high fidelity all together and just use the crappy ones that Apple supply for on the go use. I save the high quality experience for the 558's when I'm at home.