Yes, that should work. However, depending on the adapter you have, you may only get sound out of one speaker (left or right). Test this by plugging in a normal set of stereo headphones and see if you get sound out of both speakers. I purchased an adapter from radioshack and it doesn't account for the third contact (mic) so I have to plug it in halfway to get sound out of both speakers.
Something like this adapter would probably be a great combo with that cable:
http://www.semsons.com/2miusband3st.html