Don't bother replacing them. I don't know if you've heard of the new JVC HA-FX66's, but they cost about the same as the Marshmallows if you get them on sale. Anyway, they're supposedly awesome for the lower price range. I haven't tried them, but all the customer reviews I've seen (that's about fifteen) say they're secure fitting, very comfortable, have good isolation, and sound great (well except one, where the guy probably had them in wrong, since his description of the sound just didn't fit what everyone else was saying-- he gave the usual cluelessly-new-to-canalphones description of no bass and harsh treble that comes with trying to wear them like plain old ear buds).