I found an adapter to use on a standard stereo headset for listening to MP3s. It can be purchased at Fry's electronics for $1.99. Which I'm sure can be purchased at Radio Shack or an eletronic store. The rubber molding is a bit larger and might not fit in the treo socket, so you will need to shave some of the rubber using a blade so it will go in all the way into the 2.5 mm socket. I'm sure you can find other ones that might fit exactly without shaving any of the rubber molding off. Let me know if you guys want to see pictures.