Mike,
I thought I had answered your question, because some people assume that there is access to digital audio
through a USB sound card. Unfortunately, there is no such thing built-in to the RRC, so you have to use the
AUX/MIC jack. If you can hack the SIP steam, you will be a hero.
One idea: try to get a hold of version A of the 1274 RRC Micro PC Client. It has a sound card built-in and you
can take that audio stream for digital modes directly. The problem with that device would be PTT. Be careful
and don't use the 1274B, since the sound card was removed.
73,
Mitch DJ0QN / K7DX