After all the positive comments, I ordered in early August and received my set on Monday. I got a little nervous reading about the hiss issue (sounded very annoying...)
But, having tried mine over the past few days, I haven't found any _annoying_ level of hiss. Started out on my iPod video, moved to my shuffle, my wifes Gen2 nano, and my daughters brick (her backup, a 2nd gen). The hiss was barely noticeable on the shuffle, but I thought barely. Really nothing in the background on the Video or nano, and surprisingly zip on the brick. Sounds great coming directly out of my Mac MBP, too. I haven't tried the Gen 3 (4 buttons) or Gen 4, tho I know my ex-Gen 3 lacked in the sound quality dept and have read the 4s were similar to worse.
Maybe one of those versions might show background hiss that would cross over into annoying. But, so far, so happy...
BTW, great sound unamped on the Video. I am running sound volume at around 1/3rd to less than a half of the volume bar. By comparison, my UM2s keep me happy at ~40-60% and my old ER-4Ps ran 60-80%. BTW, almost all of my music was leveled by MP3Gain at around 92 (if you are familiar with it); keeps from having one song rattle your soul and another too quiet to hear...