you sometimes need to go through the pairing process 2 or 3 times before the a2dp support kicks in. there are other threads regarding this. i had to do this with my intempo set. also make sure you turn on a2dp support before starting media playhback. you can run mplayer in xterm and read the output to see what is happening.

do not forget that a2dp is not officlal on the n8x0, and therefore can be a clunky. having said that i have found tghat it's better than on my nokia phone on which a2dp is offically supported.