Not a 100% sure, so maybe somebody with more experience with the deck could help you out. On my PRS 880 I use a 3.5mm to 2.5mm cord that plugs right into it and bingo, bango.
I have to use my iPod to work it though, which is a bish. I have my adapter, but have yet to install it. I heard it is slow as balls trying to go through all the songs. That is what has kept me from installing it so far.