replace earbuds on the s series audio adapter?

[effigy345]

i noticed that sony has reduced the price on the s series accessories on sonystyle.com (50% off). i want to get the audio adapter, but before i do i'm curious as to whether or not you can replace the earbuds with different headphones. i know its a proprietary connector, but is there a converter out there somewhere?

[effigy345]

i thought i should elaborate a little as to why i'm interested in this. i want to know if i can get a converter to a regular headphone plug so that i can use one of those cassette adaptors that people use to play portable cd players in the cassette decks in their cars. i'd like to be able to play mp3s from my clie on my car stereo when i'm in it, and then use the earbuds when i'm not.