I am wiring my G3X system and came across a diagram in the install manual (Page 24-26) that cables Stereo Audio Out from the G3X GDU to the Audio Panel Music 2 inputs. I'm sure it is right, but it peaked my interest. I don't see any music inputs into the GDU. Does anyone know what audio the GDU is sending to the Audio Panel? The 5XR SirusXM receivers send music out directly to the Audio Panel Music 1 input. SXM sound doesn't pass though the GDU. Only thing I can think of is a device connecting bluetooth to the GDU and it then relays the music to the audio panel. My audio panel already has bluetooth. Is this connection useful?