Does anyone know for sure if the P8400BH is not compatible with IP-Bus aux. input adapters?

I purchased a "P.I.E Aux Input Adapter (PIO/P-RCA)" from Crutchfield. Plugged it into the IP-Bus port on the back of my P8400BH. I then plugged a RCA to 3.5mm cable into the PIO/P-RCA. Turned the P8400BH on and connected the 3.5mm plug from the cable into the headphone jack on my iPad. Nothing happened. Turned the iPad's and P8400BH's volume all the way up and did not hear a thing.

When you're on the Home display what is enabled when your iPod is plugged in? On the IP-Bus you want pins 7, 9 and 10, those are the left and right audio and ground. You should see one of the aux inputs enabled on your home display when you have a signal on that input. It doesn't or shouldn't matter the model number, IP-Bus is a Pioneer thing.

Nothing new is displayed on the source list when an aux to IP-Bus adapter is plugged in. I've tried the PAC PIO/P-RCA, Sonic Electronix's house brand IP-Bus aux input adapter and Pioneer's own CD-RB10 and none of them work leading me to the conclusion that the 8400BH just isn't compatible with these IP-Bus to aux input adapters.

On the audio side there is not much to be compatible with.. you have a left/right and common on the above ref'd pins. That is exactly what you bought when you bought the RB10. Have you called Pioneer support? I have used them for IPBus support and they gave me the info I needed. You may have a bad HU. The IPBus audio input needs to see at or below 1v to be able to internally recognize a signal on that input, that could be your problem.