Thanks Mike and Mark for you input.
You both missed the target by a mile!
There are two sub parts to the problem, CAT Control and Audio. Both of you ONLY talked about Audio.
The main problem is "How can I use RigPi with my current cable connection to my IC-7600?" Many Hams already have already have Cat and Audio connections working for digital modes.
I do NOT want to give up my digital modes that currently work on the IC-7600. I just want to add RigPi remote SSB VOICE operation, NO cable changes or changing settings in my IC-7600. My current hardware using the SignaLink and the data settings in the IC-7600 are perfect!
I do NOT believe it is possible for NON SDR rigs to do both digital data and SSB RigPi communications without changing cable connections and hardware settings in the radio. A SDR rig can do it. I am defining an SDR rig as having PC software such as PowerSDR, SmartSDR etc (Apache-Labs, Flex, etc.) and use VAC, VSP or DAX. RigPi needs to connect to the PC via TCP or USB to Serial cables plus a Null Modem cable like I have done for my Apache-Labs 100D.
I believe Howard is going to need a Disclaimer on what kind of connections RigPi can do.