My first attempt at addressing this issue for myself was a set of Sennheiser OMX 80. I use them with an iPod Shuffle (MP3 format). While they do sound quite good (especially treble and mid-range) when I initially put them on, once I start running they loosen a small bit. At that point, the bass diminishes, perhaps 33 - 50%. I've tried using the numerous attachments included, and I eventually found a combination that did help somewhat. The upside is that they have NEVER fallen off my ears, I have never needed to stop running and deal with my earphones. I have the volume adjusted to a level that allows me to hear most everything around me, while still listening to music at an enjoyable level. Considering the price point and that they solve the initial problem by staying engaged with my ears, I have little to complain about.