Garmin 496 to PM1000

I hooked my Audio chord (not the brown wire in the wiring harness) from the audio output jack on the side of my 496 to the input pins on my PM1000 ( pins 3 and 16) and I can hear the audio warning thru my intercom. The problem is that the audio is extremely weak. I've adjusted the volume on the 496 and the intercom and it makes no difference.
Im wondering if anybody else hooked the 496 to a PM1000 and experienced weak signals and if so, what's the fix?

An impedance matching transformer will do the trick. I don't have the part number handy, do some searching of the site and you will find it. Available from Radio Shack.