I haven't had any issues with mine, it's pretty young, since i bought it in August this year. They're not as well built as K712, if anything they feel cheap, but the sound is worth it.

I'm aware that some people had issues with right driver solder and i've seen a K701 demo unit with headband strings stretched to the point that they lost their use, but i would say that both of these problems are easily repairable. The headphone is not premium nor it has reputation of a durable one, but i would expect at least 2-3 years of perfect working order in caring hands.

As, again, they're bright, i'd recommend trying them before buying, and if you don't like them, return them while you can. I would first go for an amp, so that i won't have questions to the source, and then go for the headphones. It is very much to your personal preference, and if you don't like something it's absolutely is your right to, and the only way you'd know why some things are good and others aren't is experience.