Hi Dave,

I believe the IC-7100 has built-in audio CODECs so only a USB control cable is required.  The FTdx-5000 can use the optional SCU-17 interface provided by Yaesu, or you can use the RigPi Audio board.  Many users opt for the SCU-17 to cut down on the number of required cables.

The RigPi Audio board can use standard 3.5mm connectors, you don't need to use the RJ45 connector for audio in/out.

73, Howard W6HN