BlackberryGPS Audio out

I have a 8700 c and just got a gps (garmin 10 x) and the software works well. The problem I am having is the audio comes out of the speakerphone and is a bit too gargled. I want to pipe the sound out through the audio jack and into my car stereo. I got an 2.5 mm adapter and I can hear the phone when I call my voicemail through my speakers so audio out is working. The problem is i can't get the gps voice to come out of my speakers. I've tried infospace find it with the same result. Can anyone help me try to get audio out through the audio out jack.

Thanks all

Sorry i can't help, but I have done the same thing with my treo and worked well. I am hoping to use this set up with my curve. Does anyone know if it is possible?