If im repettive, sorry, i couldnt read through the whole thread, but, you might be experiencing a handful of things when you talk about distortion. If your switching from bose, chancesare your losing some bass, as well as some coloration, and your headphones may sound "brighter" than your used to. I used to have a problem with this, in time, you'll grow into the new sound and you might appreciate the brighter coloration, which chances are, is more accurate to the original recording, and really allows you to hear aspects of the music you never noticed before. You might be experiencing "clipping" when you run your ipod up too loud, ive found the point where things starts to "clip" varied from headphone to headphone, my 595 start to clip at about 70% volume on my computer for most of my metal recordings, and at around 90% for most everything else, my apple earbuds, as i remember, clipped around 50% on my laptop. Clipping, by the way, is probably the wrong term here, but the sound is similar to when you open audacity and scream into the mic.