I have an AFS4500, recently added an intercomm with switched inputs (pm3000) and the amx-2a to run some audio inputs. I have the transponder, gtn, and landing height controller all giving me audio through the headset now. I wanted to get the EFIS warnings working, so I wired pin 18 on the EFIS to pin 2 on the AMX (fixed input) and EFIS 16 to pin 15 on the AMX (audio ground).

Running the audio test on the calibration page I get no audio on from the 4500. I verified my other audio inputs were working. I have the audio files on the 4500, and the 4500 indicates that sounds are playing but nothing; volume is 100%. Any suggestions?