I'm absolutely amazed at the price of these, with a fancier/heavier enclosure and more isolation these would feel like formidable audiophile universal IEM. Right now they punch way above their weight, both figuratively and literally. They aren't prone to hissing, and I haven't heard severe frequency response deviations with multiple sources, including straight off an integrated sound card, several smartphones, Sansa Clip Zip etc. Very easy to drive.   I've destroyed several pairs of these by accident just because 9.90€ earbuds are so easy to use...